Spread spectrum communication device and spread spectrum communication method

ABSTRACT

In a compressed mode, a spread spectrum communication device interleaves bit units across multiple frames using an interleaver, reduces the spreading factor using a framing/spreading unit, outputs the compressed mode frames at a predetermined compressed mode frame timing, and increases the average transmission power in the compressed mode at a radio frequency transmitter. Furthermore, a handover between different frequencies is carried out by establishing synchronization to another frequency carrier, based on a first search code and a second search code which have been detected, and moreover, a handover between different communication systems is carried out by establishing synchronization to a GSM, based on an FCCH and a SCH which have been detected.

TECHNICAL FIELD

[0001] This invention relates to a communication device applied in acode division multiple access (CDMA) communication system and a methodthereof. More particularly this invention relates to a spread spectrumcommunication device for improving interleave transmission andtransmission power control in spread spectrum communication, and forrealizing handovers between different frequencies and a method thereof.

BACKGROUND ART

[0002] In a CDMA cellular system, because the same carrier frequency isused repeatedly in every cell there is no need for handovers betweenfrequencies within the same system. However, considering a case such aswhen existing systems are present together, there is a need forhandovers between different carrier frequencies. Three points pertainingto detailed cases are described below.

[0003] As a first point, in a cell where there is considerable traffic,a separate carrier frequency is used to accommodate the increased numberof subscribers, and a handover may be performed between those cells. Asa second point, when an umbrella cell constitution is used, differentfrequencies are allocated to large and small cells, and handovers areperformed between the cells. Then, as a third point, there are cases ofhandovers between a third generation system, such as a W(Wideband)-CDMAsystem, and a second generation system, such as a current mobiletelephone system.

[0004] When performing handovers in cases such as those mentioned above,it is necessary to detect the power of carriers at the differentfrequencies. To achieve this detection, the receiver needs to only havea structure capable of detecting two frequencies. However, thisincreases the size of the constitution of the receiver, or makes theconstitution complicated.

[0005] Furthermore, two types of handover method may be considered: amobile assisted handover (MAHO) and a network assisted handover (NAHO).Comparing the MAHO and NAHO methods, NAHO reduces the burden of themobile device, out to be successful, it should be necessary tosynchronize the mobile device and the base station, whereby theconstitution of the base station and the network becomes complicated andlarge in order to be capable of tracking each individual mobile device.

[0006] For such reasons, the realization of the MAHO method is moredesirable, but to determine whether or not to handover, it is necessaryto measure the strength of carriers of different frequencies at themobile devices. However, a CDMA cellular system differs from a timedivision multiplex access (TDMA) system used in a second generation, inthat it uses ordinarily continuous transmission for bothtransmission/reception. In this continuous transmission/receptiontechnique, unless receivers corresponding to two frequencies areprepared, it is necessary to stop the timing of the transmission or thereception and measure the other frequency.

[0007] There has been disclosed a technique relating to a compressedmode method, for time-compressing the transmission data in the usualmode and transmitting it in a short time, thereby creating some sparetime which can be utilized to measure the other frequency carrier. As anexample of this, there is Japan Patent Application National Publication(Laid-Open) (JP-A) No. 8-500475 “Non-continuous Transmission forSeamless Handovers in DS-CDMA Systems”. This application discloses amethod of realizing a compressed mode, wherein the spreading factor ofthe spreading code used is lowered to compress the transmissionduration.

[0008] The method of realizing the compressed mode according to theabove application will be explained below. FIG. 36 shows an example oftransmissions in a normal mode and a compressed mode in a conventionalCDMA system. In FIG. 36, the vertical axis represents transmissionrate/transmission power, and the horizontal axis represents time. In theexample of FIG. 36, the compressed mode transmission is inserted betweennormal transmission frames.

[0009] In the transmission in the compressed mode, a non-transmissiontiming is provided in the downlink frame, and can be set to a desiredperiod of time (duration). This non-transmission timing represents idleperiod during which the strength of the other frequency carrier ismeasured. In this way, slotted transmission can be achieved by insertingthe idle period during transmission of compressed mode frames.

[0010] In this type of compressed mode transmission, transmission powerincreases in accordance with the time ratio between the idle period andthe frame (compressed mode frame) transmission timing, and therefore, asshown in FIG. 36, the compressed mode frame is transmitted at a highertransmission power than the frame in normal transmission. As aconsequence, transmission quality can be maintained even in frametransmission in compressed mode.

[0011] In addition on the application mentioned above, as an example ofpertinent literature there is Gustafsson, M. et al: “Compressed ModeTechniques for Inter-Frequency Measurements in a Wide-band DS-CDMASystem”, Proc. of 8th IEEE PIMRC '97. This research paper disclosestechniques for realizing compressed mode in cases other than when thespreading factor is lowered, namely when the coding rate is increased,when multi-code transmission is used, and when a multi-bit transmissionmodulation system such as 16 QAM is used.

[0012] However, in conventional examples such as the applicationmentioned above, since transmissions are interleaved in units of oneframe and within one frame, the interleaving time for slottedtransmission (in the compressed mode) is more compressed than in normaltransmission. Consequently, the interleaving size is shortened whichleads to a problem of poor decoding at the reception side.

[0013] Furthermore, in conventional examples such as the literaturementioned above, since the length of interleaving time is shortened whenusing compressed mode transmission, there is increased deterioration ofsignal quality with respect to fading, and, since no TPC (transmissionpower control) command bit is sent during non-transmission, it is notpossible to achieve high-speed TPC, leaving a subsequent problem of poorsignal quality.

[0014] Furthermore, in conventional examples such as the application andliterature mentioned above, the spreading factor is lowered whencarrying out a compressed mode transmission. However, in general,lowering of the spreading factor indicates that a spreading code havinga short code-length is being used. However, since the number ofspreading codes that can be used is directly proportional to the squareof the code-length, there is a problem that there are extremely fewspreading codes having short code-lengths, and these spreading coneresources, which are vital for realizing compressed mode transmission,are consumed.

[0015] It is an object of the present invention to solve the problemsdescribed above by providing a spread spectrum communication device anda spread spectrum communication method capable of preventingdeterioration in signal quality caused by compressed mode, with respectto interleaving, transmission power control, spreading code allocationmethods and the like to minimize the effects of transmission errors.

DISCLOSURE OF THE INVENTION

[0016] A spread spectrum communication device according to an aspect ofthe present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises an interleaving unit forinterleaving in bit units a frame or a compressed frame, which is a unitof a transmission data stream, to minimize effects of transmissionerrors; a compressing/intermittent transmitting unit for compressing aframe prior to or after interleaving in the compressed mode, andmoreover, intermittently outputting the compressed frame to theinterleaving unit if the compressed frame has not yet been interleaved,and intermittently outputting the compressed frame to a device on areception side if the compressed frame has been interleaved; a controlunit for controlling the operation of interleaving in bit units of theinterleaving unit, and the compressing/intermittent transmittingoperation of the compressing/intermittent transmitting unit; the controlunit controlling the interleaving unit to perform interleaving in bitunits across multiple frames in the compressed mode.

[0017] According to this invention, in the compressed mode, multipleframes are interleaved in bit units to minimize effects of transmissionerrors, whereby it is possible to secure appropriate interleaving timein the compressed mode in the same way as in the normal mode, andconsequently, poor performance caused by interleaving in bit units canbe prevented.

[0018] A spread spectrum communication device according to a next aspectof the invention is characterized in that the interleaving unit has amemory size in correspondence with the number of frames to beinterleaved in the compressed mode.

[0019] According to this invention, since the memory size used is incorrespondence with the number of frames to be interleaved in thecompressed mode, interleaving in bit units can be performed in a numberof frames sufficient to minimize the effects of transmission errors inthe compressed mode.

[0020] A spread spectrum communication device according to a next aspectof the invention is applied in a code division multiple access systemfor continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andcharacterized in that it comprises an interleaving unit for interleavingin bit units a frame or a compressed frame, which is a unit of atransmission data stream, to minimize effects of transmission errors; acompressing/intermittent transmitting unit for compressing a frame priorto or after interleaving in the compressed mode, and moreover,intermittently outputting the compressed frame to the interleaving unitif the compressed frame has not yet been interleaved, and intermittentlyoutputting the compressed frame to a device on a reception side if thecompressed frame has been interleaved; a control unit for controllingthe interleaving operation in bit units of the interleaving unit, andthe compressing/intermittent transmitting operation of thecompressing/intermittent transmitting unit; the control unit controllingthe compressing/intermittent transmitting unit so that the compressedframe is divided to the front and rear of the same frame timing as inthe normal mode.

[0021] According to this invention, in the compressed mode, thecompressed frame is divided to the front and rear of the same frametiming as in the normal mode, and intermittently transmitted in thatarrangement, and consequently, an appropriate interleaving duration canbe secured in the compressed mode as in the normal mode using a simpleinterleaving constitution so that the effects of transmission errorscaused by interleaving in bit units can be further reduced.

[0022] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the control unitcontrols the interleaving unit so that, in the compressed mode,interleaving in bit units is performed across multiple frames.

[0023] According to this invention, in the compressed mode, sinceinterleaving is controlled so that interleaving in bit units isperformed across multiple frames, an appropriate interleaving durationcan be secured in the compressed mode as in the normal mode, andconsequently, the effects of transmission errors caused by interleavingin bit units can be further reduced.

[0024] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting multiple frames in a normal mode,and intermittently transmitting compressed frames in a compressed mode,and is characterized in that it comprises a compressing/intermittenttransmitting unit for compressing a frame, which comprises multipleslots and is a unit of a transmission data stream, and intermittentlytransmitting the compressed frame; and a control unit for controllingthe compressing/intermittent transmitting unit so as to slot thecompressed frame, and intermittently transmit the slotted frame in N (anatural number) slot units.

[0025] According to this invention, in the compressed mode, thecompressed frame is slotted, and intermittently transmitted in N slotunits, and therefore, transmission power control bits transmitted in adownlink can be received in comparatively short time intervals, wherebythe amount of transmission power control error can be reduced.

[0026] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the control unitdetermines the N slot units in accordance with the relationship betweenthe measuring time of another frequency carrier component and the amountof transmission power control error.

[0027] According to this invention, since the N slot units aredetermined in accordance with the relationship between the measuringtime of another frequency carrier strength and the amount oftransmission power control error, it is possible to secure time forreliably measuring the strength of other frequency carriers, and inaddition, the amount of transmission power control error can be greatlyreduced.

[0028] A spread spectrum communication device according to a next aspectof the present invention is characterized in that it further has aninterleaving unit for interleaving in bit units a frame or a compressedframe, which is a unit of a transmission data stream, to minimizeeffects of transmission errors; the control unit controlling theinterleaving unit so that, in the compressed mode, interleaving in bitunits is performed across multiple frames.

[0029] According to this invention, in the compressed mode, sinceinterleaving in bit units is controlled across multiple frames, anappropriate interleaving duration can be secured in the compressed modeas in the normal mode, and consequently, the effects of transmissionerrors caused by interleaving in bit units can be further reduced.

[0030] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises an interleaving unit forinterleaving in bit units a frame or a compressed frame, which is a unitof a transmission data stream, to minimize effects of transmissionerrors; a compressing/intermittent transmitting unit for compressing aframe prior to or after interleaving in the compressed mode, andmoreover, intermittently outputting the compressed frame to theinterleaving unit if the compressed frame has not yet been interleaved,and intermittently outputting the compressed frame to a device on areception side if the compressed frame has been interleaved; a controlunit for controlling the interleaving in bit units operation of theinterleaving unit, and the compressing/intermittent transmittingoperation of the compressing/intermittent transmitting unit; wherein inthe compressed mode, the control unit controls thecompressing/intermittent transmitting unit so that multiple frames priorto interleaving in bit units by the interleaving unit, or multipleframes after interleaving, are compressed using code-multiplexing in agiven frame timing.

[0031] According to this invention, in the compressed mode, multipleinterleaved frames are compressed using code-multiplexing in a givenframe timing and intermittently transmitted, whereby an appropriateinterleaving duration can be secured in the compressed mode as in thenormal mode, and consequently, performance deterioration caused byinterleaving in bit units can be prevented.

[0032] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the control unitcontrols the interleaving unit so that, in the compressed mode,interleaving is performed in bit units across multiple frames.

[0033] According to this invention, in the compressed mode, interleavingis performed in bit units across multiple frames, and therefore, alonger interleaving duration can be secured in the compressed mode thanin the normal mode, whereby the effects of transmission errors caused byinterleaving in bit units can be further reduced. In particular, ifother frames are replaced by multi-code-transmitted frames andinterleaving is performed, it is possible to disperse multiplemulti-code-transmitted frames which are in error in the same place,thereby increasing the correcting capability of the error-correctionencoding.

[0034] A spread spectrum communication device according to a next aspectof the present invention is characterized in that thecompressing/intermittent transmitting unit has a memory size incorrespondence with the number of frames to be code-multiplexed in thecompressed mode.

[0035] According to this invention, since the memory size used is incorrespondence with the number of frames to be code-multiplexed in thecompressed mode, code-multiplexing can be realized reliably and withoutloss in the compressed mode.

[0036] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, ischaracterized in that it comprises a compressing/intermittenttransmitting unit for compressing a frame, which is a unit of atransmission data stream, and intermittently transmitting the compressedframe, in the compressed mode; and a control unit for controlling thecompressing/intermittent transmitting unit so that, in the compressedmode, the compressing/intermittent transmitting unit intermittentlytransmits at a lower transmission rate than the transmission rate in thenormal mode, while using the same transmission power as in the normalmode.

[0037] According to this invention, in the compressed mode, thecompressing/intermittent transmitting unit intermittently transmits at alower transmission rate than the transmission rate in the normal mode,while using the same transmission power as in the normal mode, andconsequently, the there is less interference power on other users on thesame frequency during a frequency handover, enabling the frequencyhandover to be realized with reduced interference.

[0038] A spread spectrum communication device according to a next aspectof the present invention is characterized in that it further comprisesan interleaving unit for interleaving in bit units a frame or acompressed frame, which is a unit of a transmission data stream, tominimize effects of transmission errors; the control unit controllingthe interleaving unit so that, in the compressed mode, interleaving inbit units is performed across multiple frames.

[0039] According to this invention, in the compressed mode, interleavingin bit units is performed across multiple frames, and therefore anappropriate interleaving duration can be secured in the compressed modeas in the normal mode, and consequently, the effects of transmissionerrors caused by interleaving in bit units can be further reduced.

[0040] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the control unitcontrols the compressing/intermittent transmitting unit so that thecompressed frame is divided to the front and rear of the same frametiming as in the normal mode.

[0041] According to this invention, since the compressed frame isdivided to the front and rear of the same frame timing as in the normalmode, and intermittently transmitted in compliance with thatarrangement, an appropriate interleaving duration can be secured in thecompressed mode as in the normal mode with a simple interleaveconstitution, and consequently, deterioration in performance caused byinterleaving in bit units can be further reduced.

[0042] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the control unitcontrols the compressing/intermittent transmitting unit so as to slotthe compressed frame, and intermittently transmit the slotted frame in N(a natural number) slot units.

[0043] According to this invention, in the compressed mode, thecompressed frame is slotted and intermittently transmitted in N slotunits; therefore, transmission power control bits transmitted in adownlink can be received in comparatively short time intervals, wherebythe amount of transmission power control error can be reduced.

[0044] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a memory unit for storing optimumtransmission power control units for the normal mode and the compressedmode, so that the transmission power control unit controlling one outputof transmission power is greater in the compressed mode than in thenormal mode; and a transmission power control unit for referring to thememory unit, and controlling transmission power to a communicationpartner device in compliance with transmission power control units incorrespondence with the normal mode and the compressed mode, based oninformation representing a reception power received from thecommunication partner device.

[0045] According to this invention, in the compressed mode, transmissionpower to the communication partner device is controlled so that atransmission power control unit for one time is greater in thecompressed mode than in the normal mode, and consequently, in thecompressed mode, even when the temporal intervals of the transmissionpower control during intermittent transmission are wider, it is possibleto widen the control range of the transmission power and maintainadhesion to the transmission power in the compressed mode, whereby theamount of error of transmission power control in the compressed mode canbe reduced.

[0046] A spread spectrum communication device according to a next aspectof the present invention is characterized in that it further comprises acompressing/intermittent transmitting unit for compressing a frame,which comprises multiple slots and is a unit of a transmission datastream, and intermittently transmitting the compressed frame; and acontrol unit for controlling the compressing/intermittent transmittingunit so as to slot the compressed frame, and intermittently transmit theslotted frame in N (a natural number) slot units.

[0047] According to this invention, in the compressed mode, thecompressed frame is slotted, and intermittently transmitted in N slotunits, and therefore, transmission power control bits transmitted in adownlink can be received in comparatively short time intervals, wherebythe amount of transmission power control error can be reduced.

[0048] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a memory unit for taking moremultiple types of transmission power control unit than in the normalmode, a transmission power control controlling one input of transmissionpower, including among the multiple types of transmission power controlunit a transmission power control unit which is greater than in thenormal mode, and storing optimum transmission power control units forthe normal mode and the compressed mode; a transmission power controlunit for referring to the memory unit, and controlling transmissionpower to a communication partner device in compliance with transmissionpower control units in correspondence with the normal mode and thecompressed mode, and in addition, in correspondence with temporalintervals in the transmission power control in the compressed mode,based on information representing a reception power received from acommunication partner device.

[0049] According to this invention, transmission power to acommunication partner device is controlled in compliance withtransmission power control units in correspondence with the normal modeand the compressed mode, and in addition, in correspondence withtemporal intervals in the transmission power control in the compressedmode; therefore, even when the temporal intervals of the transmissionpower control during intermittent transmission alter, by utilizing thecontrol range of the transmission power it is possible to maintainadhesion to the transmission power in the compressed mode, therebyreducing the amount of error of transmission power control in thecompressed mode.

[0050] A spread spectrum communication device according to a next aspectof the present invention is characterized in that it further comprises acompressing/intermittent transmitting unit for compressing a frame,which comprises multiple slots and is a unit of a transmission datastream, and intermittently transmitting the compressed frame; and acontrol unit for controlling the compressing/intermittent transmittingunit so as to slot the compressed frame, and intermittently transmit theslotted frame in N (a natural number) slot units.

[0051] According to this invention, in the compressed mode, thecompressed frame is slotted, and intermittently transmitted in N slotunits, and therefore, transmission power control bits transmitted in adownlink can be received in comparatively short time intervals, wherebythe amount of transmission power control error can be greatly reduced.

[0052] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a transmission section for using adesired spreading code to create transmission data of a quantitycorresponding to a number of users who can be served thereby, incorrespondence with the normal mode and the compressed mode, and addingand transmitting the transmission data created in correspondence withthe number of users; and a compressed mode control section, connected tothe transmission section, for controlling the creation operation oftransmission data by the transmission section in the compressed mode;the compressed mode control section having a frame combining unit forextracting from given combinations of multiple compressed mode frames,compressed by separate users in the transmission section, a combinationhaving a total transmission duration of less than one frame duration; aspreading code allocation unit for allocating the same spreading code toeach of multiple channels which transmit the combination extracted bythe frame combining unit; and a transmission timing control unit forusing a single spreading code, allocated by the spreading codeallocating unit, to control the transmission section so thattransmission timings of multiple compressed mode frames, which comprisethe above extracted combination, do not temporally overlap within oneframe duration.

[0053] According to this invention, the compressed mode control sectionextracts from given combinations of multiple compressed mode frames,compressed by separate users in the transmission section, a combinationhaving a total transmission duration of less than one frame duration,allocates the same spreading code to each of multiple channels whichtransmit the combination extracted by the frame combining unit, and usesa single spreading code, allocated by the spreading code allocationunit, to control the transmission section so that transmission durationof multiple compressed mode frames, which comprise the above extractedcombination, do not temporally overlap within one frame duration;therefore, when there are multiple compressed mode frames, the number ofspreading codes with low spreading factor used in the compressed modecan be reduced, and consequently, the spreading code resources can beeffectively used in the compressed mode.

[0054] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a compressing/intermittentreceiving unit for intermittently receiving a compressed frame in thecompressed mode; search code detecting and determining unit fordetecting on other frequency carriers, during non-transmission period inthe compressed mode, a first search code, which is shared at all basestations and is time-continually transmitted, and a second search code,which is transmitted at the same timing as the first search code and canbe identified by multiple numeric patterns, and determining these searchcodes based on a predetermined reference; a control unit for selectingthe compressing/intermittent receiving unit during intermittentreceiving, selecting the search code detecting and determining unitduring non-transmission duration, and controlling operations of both;the control unit establishing synchronization to the other frequencycarrier, based on the first search code and second search code detectedby the search code detecting and determining unit, and therebycontrolling a handover between different frequencies.

[0055] According to this invention, synchronization to another frequencycarrier is established based on the first search code and second searchcode detected by the search code detecting and determining unit, therebyenabling a handover to be efficiently performed between differentW-CDMA/W-CDMA frequencies.

[0056] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the control unitcarries out control to detect at least one first search code during thenon-transmission period which is not more than half of one frame, andthereafter, carries out control to repeat the processing of shifting thenon-transmission period by a predetermined slot unit, and to detect anumeric value of all second search codes using multiple frames, and toestablish synchronization to the other frequency carrier, based on thedetected first search code and the numeric pattern of second searchcode, thereby controlling a handover between different frequencies.

[0057] According to this invention, at least one first search code isdetected during the non-transmission period which is not more than halfof one frame, and thereafter, the processing of shifting thenon-transmission period by a predetermined slot unit is repeated, anumeric value of all the second search codes is detected using multipleframes, and synchronization is established to the other frequencycarrier based on the detected first search code and the numeric patternof second search code, thereby enabling a handover to be even moreefficiently performed between different W-CDMA/W-CDMA frequencies.

[0058] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the non-transmissionduration can be arranged across multiple frames.

[0059] According to this invention, since the non-transmission periodcan be arranged across multiple frames, the second search codes can bedetected multiple times, improving the reliability of the detectedcodes.

[0060] A spread spectrum communication device according to a next aspectof the present invention is characterized in that, when no search codecan be obtained which satisfies a predetermined level of reliabilityduring the search code detection, a search code is detected again in theplace.

[0061] According to this invention, when no search code can be obtainedwhich satisfies a predetermined level of reliability during the searchcode detection, a search code is detected again in the place, andconsequently, synchronization can be established based on information ofhigh reliability.

[0062] A spread spectrum communication device according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a compressing/intermittentreceiving unit for intermittently receiving a compressed frame in thecompressed mode; information detecting and determining unit fordetecting in another communication system, during non-transmissionperiod in the compressed mode, a first information for matchingfrequencies, and a second information for achieving synchronization, anddetermining the first and second information based on a predeterminedreference; a control unit for selecting the compressing/intermittentreceiving unit during intermittent receiving, selecting the informationdetecting and determining unit during non-transmission period, andcontrolling operations of both; the control unit establishingsynchronization to the other communication system, based on the firstinformation and second information detected by the information detectingand determining unit, and thereby controlling a handover betweendifferent frequencies.

[0063] According to this invention, synchronization to anothercommunication system is established based on the first information andsecond information detected by the information detecting and determiningunit, thereby enabling a handover between different frequencies to beachieved efficiently.

[0064] A spread spectrum communication device according to a next aspectof the present invention is characterized in that the control unitcarries out control to detect at least one first information during thenon-transmission period which is not more than half of one frame,thereafter, carries out control to set the non-transmission period basedon a time found by the detected first information, and to detect thesecond information, and establishes synchronization to the othercommunication system, based on the detected first information and secondinformation, thereby controlling a handover between differentfrequencies.

[0065] According to this invention, a least one first information isdetected during the non-transmission period which is not more than halfof one frame, thereafter, the non-transmission period is set based on atime found by the detected first information, the second information isdetected, and synchronization to the other communication system isestablished based on the detected first information and secondinformation; therefore, a handover between different systems can becarried out more effectively.

[0066] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of interleaving ofinterleaving bit units across multiple frames, in order to minimizeeffects of transmission errors, in the compressed mode; a second step ofcompressing a frame interleaved in bit units in the first step, andintermittently transmitting it.

[0067] According to this invention, in the compressed mode, in order tominimize effects of transmission errors, interleaving of bit units isperformed across multiple frames, and the interleaved frame iscompressed and intermittently transmitted; therefore, an appropriateinterleaving duration can be secured in the compressed mode as in thenormal mode, and consequently, deterioration in performance caused byinterleaving in bit units can be prevented.

[0068] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of compressing aframe, which is a unit of a transmission data stream, and intermittentlyoutputting it, in the compressed mode; and a second step of interleavingbit units across a plurality of the compressed frames.

[0069] According to this invention, in the compressed mode, a frame,which is a unit of a transmission data stream, is compressed and outputintermittently, and interleaving in bit units is performed acrossmultiple compressed frames; consequently, therefore, an appropriateinterleaving duration can be secured in the compressed mode as in thenormal mode, and deterioration in performance caused by interleaving inbit units can be prevented.

[0070] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of interleaving bitunits of a frame, which is a unit of a transmission data stream, andintermittently outputting it, in order to minimize effects oftransmission errors; and a second step, performed in the compressedmode, of compressing a frame interleaved in bit units in the first step,dividing the compressed frame to the front and rear of the same frametiming as in the normal mode, and intermittently transmitting it.

[0071] According to this invention, in the compressed mode, a frameinterleaved in bit units is compressed, divided to the front and rear ofthe same frame timing as in the normal mode, and intermittentlytransmitted; consequently, an appropriate interleaving duration can besecured in the compressed mode as in the normal mode, wherebyperformance deterioration caused by interleaving in bit units can beprevented.

[0072] A spread spectrum communication method according to the presentinvention is applied in a code division multiple access system forcontinuously transmitting frames in a normal mode, and intermittentlytransmitting compressed frames in a compressed mode, and ischaracterized in that it comprises a first step, performed in thecompressed mode, of compressing a frame, which is a unit of atransmission data stream, and interleaving bit units of the compressedframe; and a second step of dividing the compressed and interleavedframe to the front and rear of the same frame timing as in the normalmode, and intermittently transmitting it.

[0073] According to this invention, in the compressed mode, a frame,which is a unit of a transmission data stream, is compressed andinterleaved in bit units, divided to the front and rear of the sameframe timing as in the normal mode, and intermittently transmitted;consequently, an appropriate interleaving duration can be secured in thecompressed mode as in the normal mode, whereby performance deteriorationcaused by interleaving in bit units can be prevented.

[0074] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of dividing a frame,being a unit of a transmission data stream, into multiple slots in thecompressed mode; and a second step of intermittently transmitting theframe slotted in the first step in N (N=a natural number) slot units.

[0075] According to this invention, in the compressed mode, thecompressed frame is slotted, and intermittently transmitted in N slotunits, and therefore, transmission power control bits transmitted in adownlink can be received in comparatively short time intervals, wherebythe amount of transmission power control error can be greatly reduced.

[0076] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of interleaving inbit units a frame, being a unit of a transmission data stream, in orderto minimize effects of transmission errors; a second step, performed inthe compressed mode, of using code-multiplexing to compress, in a givenframe timing, multiple frames interleaved in bit units in the firststep, and transmit them intermittently.

[0077] According to this invention, in the compressed mode,code-multiplexing is used to compress, in a given frame timing, multipleframes interleaved in bit units, and they are transmittedintermittently; consequently, an appropriate interleaving duration canbe secured in the compressed mode as in the normal mode, wherebyperformance deterioration caused by interleaving in bit units can beprevented.

[0078] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step, performed in thecompressed mode, of using code-multiplexing to compress, in a givenframe timing, multiple frames interleaved in bit units in the firststep, and transmit them intermittently; and a second step ofinterleaving the compressed frames in bit units.

[0079] According to this invention, in the compressed mode,code-multiplexing is used to compress, in a given frame timing, multipleframes interleaved in bit units, and they are transmittedintermittently; consequently, an appropriate interleaving duration canbe secured in the compressed mode as in the normal mode, wherebyperformance deterioration caused by interleaving in bit units can beprevented.

[0080] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of compressing aframe, which is a unit of a transmission data stream, in the compressedmode; and a second step of using the same transmission power as in thenormal mode to transmit the frame compressed in the first step at alower transmission rate than in the normal mode.

[0081] According to this invention, in the compressed mode, the sametransmission power as in the normal mode is used to intermittentlytransmit a compressed frame at a lower transmission rate than in thenormal mode; therefore, during a handover between frequencies, theamount of interference power to other users on the same frequency isreduced, whereby a handover between frequencies with reducedinterference can be achieved.

[0082] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of receivinginformation representing received power from a communication partnerdevice; a second step of preparing beforehand a table storing optimumtransmission power control units for the normal mode and the compressedmode, so that the transmission power control unit controlling one inputof transmission power is greater in the compressed mode than in thenormal mode, referring to the table, and determining transmission powerfor the normal mode and the compressed mode, based on the informationrepresenting received power received in the first step; and a third stepof transmitting to the communication partner device in compliance withthe transmission power determined in the second step.

[0083] According to this invention, by referring to a table storingoptimum transmission power control units for the normal mode and thecompressed mode, so that the transmission power control unit controllingone input of transmission power is greater in the compressed mode thanin the normal mode, based on the information representing received powerreceived from a communication partner device, transmission powers forthe normal mode and the compressed mode are determined, and in thecompressed mode, transmission is carried out so that the transmissionpower control unit controlling one input of transmission power isgreater in the compressed mode than in the normal mode; therefore, inthe compressed mode, even when the temporal intervals of thetransmission power control during intermittent transmission are wider,it is possible to widen the control range of the transmission power andmaintain adhesion to the transmission power in the compressed mode,whereby the amount of error of transmission power control in thecompressed mode can be reduced.

[0084] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of receivinginformation representing received power from a communication partnerdevice; a second step of taking more multiple types, of transmissionpower control unit than in the normal mode, a transmission power controlcontrolling one input of transmission power, including among themultiple types of transmission power control unit a transmission powercontrol unit which is greater than in the normal mode, preparingbeforehand a table storing optimum transmission power control units forthe normal mode and the compressed mode, referring to the memory unit,and determining transmission power in correspondence with the normalmode and the compressed mode, and in addition, in correspondence withtemporal intervals in the transmission power control in the compressedmode, based on information representing a received power received in thefirst step; and a third step of transmitting to the communicationpartner device in compliance with the transmission power determined inthe second step.

[0085] According to this invention, with regard to a transmission powercontrol unit controlling one input of transmission power, more multipletypes of these transmission power control units are taken than in thenormal mode, including among the multiple types of transmission powercontrol unit a transmission power control unit which is greater than inthe normal mode, a table storing optimum transmission power controlunits for the normal mode and the compressed mode is referred to, andtransmission power is determined in correspondence with the normal modeand the compressed mode and in addition, in correspondence with temporalintervals in the transmission power control in the compressed mode,based on information representing a reception power received from thecommunication partner device; and transmission is carried out incompliance with the determined transmission powers; therefore, in thecompressed mode, even when the temporal intervals of the transmissionpower control during intermittent transmission alter, by utilizing thecontrol range of the most suitable transmission power it is possible tomaintain adhesion to the transmission power, thereby reducing the amountof error of transmission power control in the compressed mode.

[0086] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first step of compressingframes, being units of a transmission data stream, in multipletransmission channels performing compressed mode transmission; a secondstep of extracting from given combinations of multiple compressed modeframes, compressed separately for users in the first step, a combinationhaving a total transmission duration of less than one frame duration; athird step of allocating the same spreading code to each of multiplechannels which transmit the combination extracted in the second step;and a fourth step of using the same spreading code, allocated in thethird step, to transmit multiple compressed mode frames, which comprisethe combination extracted in the second step, so that their transmissionduration do not temporally overlap within one frame duration.

[0087] According to this invention, in multiple transmission channelswhere compressed mode transmission is being performed, frames which areunits of a transmission data stream are compressed; a combination havinga total transmission duration of less than one frame duration isextracted from given combinations of multiple compressed mode frames,compressed separately for users; the same spreading code is allocated toeach of multiple channels which transmit the extracted combination; andthe same spreading code is used to transmit multiple compressed modeframes, comprising the extracted combination, so that their transmissionduration do not temporally overlap within one frame duration; therefore,the number of spreading codes with low spreading factor used in thecompressed mode can be reduced, and consequently, the spreading coderesources can be effectively used in the compressed mode.

[0088] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first search code detecting stepof detecting at least one first search code during the non-transmissionperiod which is not more than half of one frame; a second search codedetecting step of thereafter repeating the processing of shifting thenon-transmission period by a predetermined slot unit, and detecting anumeric value of all second search codes using multiple frames; ahandover between different frequencies being controlled by establishingsynchronization to another frequency carrier, based on the detectedfirst search code and the numeric pattern of second search code.

[0089] According to this invention, at least one first search code isdetected during the non-transmission period which is not more than halfof one frame, thereafter, the process of shifting the non-transmissiontiming by a predetermined slot unit is repeated, a numeric value of allsecond search codes is detected using multiple frames, and based on thedetected first search code and the numeric pattern of second searchcode, synchronization is established to another frequency carrier;consequently, a handover between different W-CDMA/W-CDMA frequencies canbe effectively performed.

[0090] A spread spectrum communication method according to a next aspectof the present invention is characterized in that the non-transmissionperiod can be arranged across multiple frames.

[0091] According to this invention, since the non-transmission periodcan be arranged across multiple frames, the second search codes can bedetected multiple times, improving the reliability of the detectedcodes.

[0092] A spread spectrum communication method according to a next aspectof the present invention is characterized in that, when no search codecan be obtained which satisfies a predetermined level of reliabilityduring the search code detection, a search code is detected again in theplace.

[0093] According to this invention, when no search code can be obtainedwhich satisfies a predetermined level of reliability during the searchcode detection, a search code is detected again in the place, enablingsynchronization to be established based on information of highreliability.

[0094] A spread spectrum communication method according to a next aspectof the present invention is applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, andis characterized in that it comprises a first information detecting stepof detecting a first information for matching frequencies duringnon-transmission period which is not more than half of one frame; asecond information detecting step of detecting second information forsetting the non-transmission duration, based on a known timingdetermined beforehand from the detected first information, and achievingsynchronization; a handover between different frequencies beingcontrolled by establishing synchronization to another communicationsystem, based on (the detected first information and second information.

[0095] According to this invention, at least one first information isdetected during the non-transmission period which is not more than halfof one frame, thereafter, the non-transmission period is set based on aknown timing found by the detected first information, the secondinformation is detected, and synchronization to the other communicationsystem is established based on the detected first information and secondinformation; therefore, a handover between different systems can becarried out more effectively.

BRIEF DESCRIPTION OF THE DRAWINGS

[0096]FIG. 1 is a block diagram showing a CDMA system according to afirst embodiment of the present invention;

[0097]FIG. 2 is a diagram explaining memory distribution of aninterleaver according to the first embodiment;

[0098]FIG. 3 is a diagram explaining frame transmission of a downlinkaccording to the first embodiment;

[0099]FIG. 4 is a flowchart explaining a transmission operation in anormal mode according to the first embodiment;

[0100]FIG. 5 is a flowchart explaining a transmission operation in acompressed mode according to the first embodiment;

[0101]FIG. 6 is a flowchart explaining a reception operation in thenormal mode according to the first embodiment;

[0102]FIG. 7 is a flowchart explaining a reception operation in thecompressed mode according to the first embodiment;

[0103]FIG. 8 is a block diagram showing primary parts of a CDMA systemaccording to a second embodiment of the present invention;

[0104]FIG. 9 is a diagram explaining frame transmission of a downlinkaccording to the second embodiment;

[0105]FIG. 10 is a flowchart explaining a transmission operation in thecompressed mode according to the second embodiment;

[0106]FIG. 11 is a flowchart explaining a reception operation in thecompressed mode according to the second embodiment;

[0107]FIG. 12 is a diagram explaining frame transmission of a downlinkaccording to a third embodiment;

[0108]FIG. 13 is a flowchart explaining a transmission operation in thecompressed mode according to the third embodiment;

[0109]FIG. 14 is a flowchart explaining a reception operation in thecompressed mode according to the third embodiment;

[0110]FIG. 15 is a block diagram showing a CDMA system according to afourth embodiment of the present invention;

[0111]FIG. 16 is a diagram explaining memory distribution of aframing/spreading unit according to the fourth embodiment;

[0112]FIG. 17 is a diagram explaining frame transmission of a downlinkaccording to the fourth embodiment;

[0113]FIG. 18 is a flowchart explaining a transmission operation in thecompressed mode according to the fourth embodiment;

[0114]FIG. 19 is a flowchart explaining a reception operation incompressed mode according to the fourth embodiment;

[0115]FIG. 20 is a block diagram of a CDMA system according to a fifthembodiment of the present invention;

[0116]FIG. 21 is a diagram explaining frame transmission of a downlinkaccording to the fifth embodiment;

[0117]FIG. 22 is a flowchart explaining a transmission operation in thecompressed mode according to the fifth embodiment;

[0118]FIG. 23 is a flowchart explaining a reception operation in thecompressed mode according to the fifth embodiment;

[0119]FIG. 24 is a diagram explaining frame transmission of a downlinkaccording to a sixth embodiment of the present invention;

[0120]FIG. 25 is a flowchart explaining a transmission operation in thecompressed mode according to the sixth embodiment;

[0121]FIG. 26 is a flowchart explaining a reception operation in thecompressed mode according to the sixth embodiment;

[0122]FIG. 27 is a block diagram showing a CDMA system according to aseventh embodiment of the present invention;

[0123]FIG. 28 is a diagram showing the relationship between transmissionpower control symbol and transmission power control amount according tothe seventh embodiment;

[0124]FIG. 29 is a flowchart explaining a transmission power controloperation in the compressed mode according to the seventh embodiment;

[0125]FIG. 30 is a diagram showing the relationship between transmissionpower control symbol and transmission power control amount according toan eighth embodiment of the present invention;

[0126]FIG. 31 is a flowchart explaining a transmission power controloperation in the compressed mode according to the eighth embodiment;

[0127]FIG. 32 is a block diagram showing a CDMA system according to aninth embodiment of the present invention;

[0128]FIG. 33 is a diagram explaining frame transmission of a downlinkaccording to the ninth embodiment;

[0129]FIG. 34 is a flowchart explaining a transmission power controloperation in the compressed mode according to the ninth embodiment ofthe present invention;

[0130]FIG. 35 is a flowchart explaining a compressed mode controloperation according to the ninth embodiment;

[0131]FIG. 36 is a diagram explaining conventional frame transmission ofa downlink;

[0132]FIG. 37 is a diagram showing a frame constitution of a broadcastchannel (BCH);

[0133]FIG. 38 is a detailed example of detecting a second search code insixteen consecutive slots;

[0134]FIG. 39 is a table showing a correspondence between the secondsearch codes and the scrambling code groups;

[0135]FIG. 40 is a flowchart when synchronization establishmentprocedure is carried out at the mobile station side;

[0136]FIG. 41 is a diagram showing a constitution of a receiveraccording to a tenth embodiment of the present invention;

[0137]FIG. 42 is a diagram showing an outline of the operation of areceiver according to the present invention;

[0138]FIG. 43 is a flowchart when synchronization establishmentprocedure is carried out at the mobile station side in a handoverbetween different frequencies W-CDMA/W-CDMA;

[0139]FIG. 44 shows an example of obtaining a second search code;

[0140]FIG. 45 shows an example of obtaining a second search code;

[0141]FIG. 46 shows an example of obtaining a second search code;

[0142]FIG. 47 shows an example of obtaining a second search code;

[0143]FIG. 48 shows constitution of a GSM superframe;

[0144] and FIG. 49 is a flowchart when synchronization establishmentprocedure is carried out at the mobile station side in a handoverbetween W-CDMA/W-CDMA of different frequencies.

BEST MODES FOR CARRYING OUT THE INVENTION

[0145] To explain the present invention in more detail, it will bedescribed with reference to the accompanying drawings.

[0146] To begin with, the constitution of a CDMA system will beexplained. FIG. 1 is a block diagram showing a CDMA system according toa first embodiment of the present invention. The CDMA system comprises atransmitter 1A and a receiver 2A. Such a CDMA system is provided withboth base station and mobile stations. The base station and the mobilestations carry out radio communication using a CDMA communicationmethod.

[0147] The transmitter 1A, as shown in FIG. 1, comprises a controller11A, an error-correction encoder 12, an interleaver 13, aframing/spreading unit 14A, a radio frequency transmitter 15, etc.Through negotiations with the receiver 2A, the controller 11Aprincipally controls the operations of the interleaver 13, theframing/spreading unit 14A, and the radio frequency transmitter 15.Through negotiations with the receiver 2A, this controller 11Ainstructs, using frame numbers, objects for interleaving appropriate fora normal mode (a non-compressed mode) and compressed mode. Furthermore,this controller 11A instructs a transmission timing to theframing/spreading unit 14A, in order to reduce the spreading factor andtransmit a compressed mode frame in the compressed mode. Furthermore,the controller 11A instructs to the radio frequency transmitter 15 toincrease the average transmission power when transmitting the compressedmode frame.

[0148] The error-correction encoder 12 error-correct encodes thetransmitted data stream, thereby obtaining coded data. In order to beable to minimize the effect of transmission errors when continuous bitsof a transmitted signal are lost or the like, for instance as a resultof fading, the interleaver 13 interleaves the temporal sequence of thecoded data in bit units.

[0149] This interleaver 13 has a memory for interleaving two frames.When the controller 11A has instructed frame number “1” forinterleaving, the interleaver 13 interleaves one frame in the normalmode. On the other hand, when the frame number “2” has been instructed,the interleaver 13 interleaves across two frames in the compressed mode.

[0150] The framing/spreading unit 14A spreads the band in correspondencewith the normal mode and the compressed mode, using a spreading code foreach user, and forms a frame corresponding to each mode. When thecontroller 11A has instructed transmission timing in correspondence witheach of the modes, the framing/spreading unit 14A sends the frame to theradio frequency transmitter 15 in accordance with the instructedtransmission timing.

[0151] Furthermore, in the compressed mode, the framing/spreading unit14A receives a command from the controller 11A to reduce the spreadingfactor, and obtains a transmission signal using a lower spreading factorthan the normal mode, in accordance with that command. The radiofrequency transmitter 15 converts the transmission signal obtained bythe framing/spreading unit 14A to a radio frequency, and transmits it.In compliance with the controller 11A, this radio frequency transmitter15 outputs the transmission signal after increasing the averagetransmission power in the compressed mode to higher than that in thenormal mode.

[0152] As shown in FIG. 1, the receiver 2A comprises a controller 21A,an error-correction decoder 22, a deinterleaver 23, adeframing/de-spreading unit 24A, a radio frequency receiver 25, etc.Through negotiations with the transmitter 1A, the controller 21Aprincipally controls the operations of the deinterleaver 23 and thedeframing/de-spreading unit 24A. Through negotiations with thetransmitter 1A, the controller 21A specifies, using frame numbers,objects for deinterleaving appropriate for the normal mode and thecompressed mode. Furthermore, this controller 21A instructs atransmission timing to the deframing/de-spreading unit 24A, in order toreduce the spreading factor and transmit a compressed mode frame in thecompressed mode. Furthermore, in the compressed mode, the controller 11Ainstructs to the radio frequency transmitter 15 a decrease in thespreading factor and a reception timing for receiving the compressedmode frame.

[0153] The radio frequency receiver 25 demodulates received signals sentfrom an antenna not shown in the diagram. The deframing/de-spreadingunit 24A de-spreads using spreading codes allocated to the users of thereceiver 2A in correspondence with normal mode and compressed mode, andcreates a frame for each mode. When the controller 21A specifies thereception timings for each mode, the deframing/de-spreading unit 24Aextracts a reception signal from the radio frequency receiver 25 at theinstructed timing. Furthermore, in the compressed mode, thedeframing/de-spreading unit 24A receives a command from the controller11A to reduce the spreading factor, and obtains a reception signal usinga lower spreading factor than in the normal mode, in accordance withthat command.

[0154] The deinterleaver 23 interleaves the temporal sequence of thecoded data in bit units, in the reverse order to the interleaving in thetransmitter 1A (deinterleaving). Like the interleaver 13 mentionedabove, the deinterleaver 23 has a memory for deinterleaving two frames.When the controller 21A has instructed frame number “1” fordeinterleaving, the deinterleaver 23 deinterleaves one frame in normalmode. On the other hand, when the frame number “2” has been instructed,the deinterleaver 23 deinterleaves across two frames in the compressedmode. The error-correction decoder 22 error-correct decodes thedeinterleaved signal, thereby obtaining a decoded data, i.e. a receiveddata stream.

[0155] Next, the interleaver 13 and the deinterleaver 23 will beexplained. FIG. 2 is a diagram explaining memory distribution of theinterleaver according to the first embodiment, FIG. 2(a) illustrates thearea used in normal mode, and FIG. 2(b) illustrates the area used incompressed mode. In FIG. 2, a memory 131A provided with the interleaver13 is shown. The deinterleaver 23 also comprises a memory having thesame memory size as that of the interleaver 13. In the first embodiment,since interleaving is performed across two frames in the compressedmode, two-frame memory sizes in correspondence with an interleaving sizecorresponding to two frames are set in the interleaver 13 and thedeinterleaver 23 respectively.

[0156] When interleaving (see FIG. 2(a)) in normal mode, only one frame(half) of the memory 131A is used, and interleaving is performed withinthat frame. By contrast, in compressed mode (see FIG. 2(b)), two frames(all) of the memory 131A are used, and interleaving is performed inthose two frames. Similarly, in the deinterleaver 23, the area of memoryused is altered in correspondence with the mode, as in the interleaver.

[0157] Next, frame transmission including compressed mode will beexplained. FIG. 3 is a diagram explaining frame transmission of adownlink according to the first embodiment. In FIG. 3, the vertical axisrepresents transmission rate/transmission power, and the horizontal axisrepresents time. Furthermore, in FIG. 3, F represents one frame. In aCDMA system, during normal transmission, a period of time is provided toslot the frame and transmit it intermittently, and the strength of theother frequency carriers is measured using non-transmission durationduring that period.

[0158] For this purpose, the slotted frame must be compressed, and asshown in FIG. 3, the transmission duration of a compressed frame is halfof the normal transmission duration. In this case, if interleaving isperformed in the same manner as in normal transmission, there will onlybe half the necessary interleaving time, making it impossible to achieveadequate interleaving effects.

[0159] Accordingly, to secure sufficient time for interleaving, incompressed mode the transmitter 1A and the receiver 2A double the areasused in the memories of the interleaver 13 and the deinterleaver 23, andinterleave across two frames. The interleaving time needed in compressedmode can be determined easily from the ratio between the size of oneframe and the compressed mode frame.

[0160] Next, the transmission operation of the transmitter 1A will beexplained. FIG. 4 is a flowchart explaining a transmission operation Innormal mode, and FIG. 5 is a flowchart explaining a transmissionoperation in compressed mode. The execution of the operations of FIG. 4and FIG. 5 is controlled by the controller 11A, the individualoperations being performed by various sections.

[0161] In the normal mode (see FIG. 4), frame number “1” is instructedto the interleaver 13 (Step S101), and the interleaver 13 interleavesone frame. Then, when the time reaches to a time required fortransmitting one frame (Step S102), a transmission on next frame isinstructed to the framing/spreading unit 14A (Step S103). In this way,in normal mode, frames are transmitted continuously.

[0162] Furthermore, in the compressed mode (see FIG. 5), multipleframes, that is, frame number “2” is instructed to the interleaver 13(Step S111), and the interleaver 13 interleaves across two frames. Then,when the time reaches to a time required for transmitting a half-frame,that is, compressed mode frame timing (Step S112), a reduction in thespreading factor and a transmission timing are instructed to theframing/spreading unit 14A (Step S113). Moreover, an increase in theaverage transmission power is instructed to the radio frequencytransmitter 15 (Step S114). In this way, in the compressed mode, framesare transmitted intermittently (non-continuously).

[0163] Text, the reception operation of the receiver 2A will beexplained. FIG. 6 is a flowchart explaining the reception operation innormal mode, and FIG. 7 is a diagram explaining the reception operationin compressed mode. The operations of FIG. 6 and FIG. 7 are executedunder the control of the controller 21A although the individualoperations are performed by various sections. In the normal mode (seeFIG. 6), when the time reaches one frame timing (Step S121), a receptiontiming is instructed to the deframing/de-spreading unit 24A (Step S122).Then, a frame number “1” is instructed to the deinterleaver 23 (StepS123), and the deinterleaver 23 deinterleaves one frame. In this way, innormal mode, frames are received continuously.

[0164] Furthermore, in the compressed mode (see FIG. 7), when the timereaches a half-frame, that is, compressed mode frame timing (Step S131),a reduction in the spreading factor and a reception timing areinstructed to deframing/de-spreading unit 24A (Step S132). Then,multiple frames, that is, frame number “2” is instructed to thedeinterleaver 23 (Step S133), and the deinterleaver 23 deinterleavesacross two frames. In this way, in the compressed mode, frames arereceived intermittently (non-continuously).

[0165] As described above, according to the first embodiment, incompressed mode, interleaving bit units crossing multiple frames arecontrolled in order to minimize the effects of transmission errors,thereby making it possible to secure appropriate interleaving time inthe compressed mode as in the normal mode. As a consequence, it ispossible to prevent poor performance caused by interleaving of bitunits.

[0166] Furthermore, since the memory size corresponds to the number offrames to be interleaved in the compressed mode, it is possible tointerleave bits units in a number of frames sufficient to minimize theeffects of transmission errors when transmission in the compressed mode.

[0167] In the first embodiment described above, the size of the memoryfor interleaving and deinterleaving in the compressed mode is increased,securing an appropriate interleaving time in correspondence with thesize of the interleaving, but the present invention is not restricted tothis, and it is acceptable to secure an appropriate interleaving time bychanging the method of transmitting the compressed mode frame withoutincreasing the size of the memory, as in a second embodiment explainedlater. Since the entire constitution of the second embodiment of thepresent invention is the same as the first embodiment already explained,the following description covers only those features of the constitutionand operation which differ from the first embodiment. Furthermore,identical components are represented by the same reference numerals.

[0168] Here, only the primary constitution will be explained. FIG. 8 isa block diagram showing primary parts of a CDMA system according to thesecond embodiment of the present invention. In the CDMA system of thesecond embodiment, the difference from the first embodiment alreadydescribed is the size of the memory 131B of the interleaver 13, whichhere is one frame. Furthermore, although not depicted in the diagram,the deinterleaver 23 of the receiver also has a memory size of oneframe, to match that of the interleaver 13.

[0169] Next, frame transmission including the compressed mode will beexplained. FIG. 9 is a diagram explaining frame transmission of adownlink according to the second embodiment. In FIG. 9, the verticalaxis represents transmission rate/transmission power, and the horizontalaxis represents time. In the CDMA system, during normal transmission, aperiod of time is provided to slot the frame and transmit itintermittently, and the strength of the other frequency carriers ismeasured using the fact that frames are not transmitted during thatperiod. For this purpose, the slotted frame must be compressed, but ifinterleaving is performed in the same manner as in normal transmission,the interleaving time will be insufficient, and it will be impossible toobtain an adequate interleaving effect.

[0170] Accordingly, the transmission timing of the compressed frame isdivided, and one part is allocated to the head of the frame, the otheris allocated to the end of the same frame, securing the desiredinterleaving time. At the receiver, this operation is performed inreverse. As in the first embodiment, the time needed for interleaving incompressed mode can be determined easily from the ratio between the sizeof one frame and the compressed mode frame.

[0171] Next, the operation will be explained. Here, only the operationin compressed mode will be explained. FIG. 10 is a flowchart explainingthe transmission operation in compressed mode, and FIG. 11 is aflowchart explaining the reception operation in compressed mode. In thecompressed mode (see FIG. 10) at the transmitter, interleaving in oneframe is instructed to the interleaver 13 (Step S201), and theinterleaver 13 interleaves one frame.

[0172] Then, when the time reaches any one of the front and rear timingsof the one-frame timing (Step S202), a transmission timing is instructedto the framing/spreading unit 14A (Step S203). Moreover, an increase inthe average transmission power is instructed to the radio frequencytransmitter 15 (Step S204), and the compressed mode frame isframe-transmitted at high transmission power. In this way, frames aretransmitted intermittently (non-continuously) in the compressed mode.

[0173] On the other hand, in the compressed mode at the receiver (seeFIG. 11), when the time reaches any one of the front and rear timings ofthe one-frame timing (Step S211), a reception timing is instructed tothe deframing/de-spreading unit 24A (Step S212). Then, after the signalof one frame has been received, a one-frame deinterleaving is instructedto the deinterleaver 23 (Step S213), and the deinterleaver 23deinterleaves one frame. In this way, frames are received intermittently(non-continuously) in the compressed mode.

[0174] As explained above, according to the second embodiment, in thecompressed mode, a frame which has been interleaved in bit units iscompressed, arranged into front and rear in the same frame timing as innormal mode, and intermittently transmitted in compliance with thatarrangement. Therefore, it is possible to secure an appropriateinterleaving time in compressed mode, in the same way as in normal mode,with a simple interleaving constitution. Consequently, poor performancecaused by interleaving in bit units can be prevented.

[0175] Furthermore, it is also possible in the second embodiment toprepare the memory sizes shown in FIG. 2, and control interleaving ofbit units crossing multiple frames in the compressed mode. In this case,as in the first embodiment described above, it is possible to secure anappropriate interleaving time in the compressed mode, as in the normalmode, and to reduce transmission errors resulting from interleaving inbit units.

[0176] In the first embodiment already explained, to performinterleaving and deinterleaving in the compressed mode, the size ofmemory is increased and an interleaving time appropriate for the size ofthe interleaving is secured, but the present invention is not restrictedto this, and it is acceptable to secure an appropriate interleaving timeby a compressed mode frame transmission method different to that of thesecond embodiment described above, as in a third embodiment describedbelow. Since the entire constitution of the third embodiment of thepresent invention is the same as the second embodiment alreadyexplained, the following description covers only those features of theoperation which differ from the second embodiment.

[0177] Firstly, frame transmission including compressed mode will beexplained. FIG. 12 is a diagram explaining frame transmission of adownlink according to the third embodiment. In FIG. 12, the verticalaxis represents transmission rate/transmission, power, and thehorizontal axis represents time. In the CDMA system, during normaltransmission, a period of time is provided to slot the frame andtransmit intermittently, and the strength of other frequency carriers ismeasured using the fact that frames are not transmitted during thatperiod. For this purpose, the slotted frame must be compressed, but ifinterleaving is performed in the same manner as in normal transmission,there will only be half the necessary interleaving time, making itimpossible to achieve adequate interleaving effects.

[0178] Accordingly, the transmission duration of he compressed frame isdivided in correspondence with multiple slots, and the non-transmissionperiod (idle period for measuring) is reduced so as not to affect thetransmission power control, securing the desired t me for interleaving.In the receiver, this operation is performed in reverse. As in the firstembodiment, the time needed for interleaving in compressed mode can bedetermined easily from the ratio between the size of one frame and thecompressed mode frame.

[0179] Furthermore, the slot number N (where N is a natural number)forming the transmission unit in compressed mode is determined inaccordance with the relationship between the measuring time of thestrength of other frequency carriers and the transmission power controlmargin of error. For instance, when N=1 it indicates every slot, N=2indicates every two slots, and N=4 indicates every four slots. Here,N=1, 2, and 4 are just the examples and it is also possible to handleother slot numbers.

[0180] Next, the operation will be explained. Here, only the operationin compressed mode will be explained. FIG. 13 is a flowchart explainingthe transmission operation in compressed mode, and FIG. 14 is aflowchart explaining the reception operation in compressed mode. In thecompressed mode at the transmitter (see FIG. 13), interleaving in oneframe is instructed to the interleaver 13 and the interleaver 13interleaves one frame (Step S301).

[0181] Then, when the time reaches the N slot timing which forms thetransmission unit in the compressed mode (Step S302), a transmissiontiming is instructed to the framing/spreading unit 14A (Step S303).Moreover, an increase in the average transmission power is instructed tothe radio frequency transmitter 15 (Step S304), and the compressed modeframe is frame-transmitted at high transmission power. In this way,frames are transmitted intermittently (non-continuously) in thecompressed mode.

[0182] On the other hand, in the compressed mode of the receiver (seeFIG. 14) when the time reaches the N slot timing (Step S311), areception timing is instructed to the deframing/de-spreading unit 24A(Step S312). Then, after the signal of one frame has been received, aone-frame deinterleaving is instructed to the deinterleaver 23 (StepS313), and the deinterleaver 23 deinterleaves one frame. In this way,frames are received intermittently (non-continuously) in the compressedmode.

[0183] As explained above, according to the third embodiment, in thecompressed mode, since a compressed frame is slotted and intermittentlytransmitted in N slot units, it is possible to receive transmissionpower control bits transmission in the downlink in comparatively shorttime intervals. In this way, by controlling ON/OFF of each N slot, themargin of error of transmission power control can be reduced.

[0184] In particular, since the N slot unit is determined in accordancewith the relationship between the measuring time of the strength ofother frequency carriers and the transmission power control margin oferror, it is possible to secure time in which the strength of otherfrequency carriers can be reliably measured, and also to reduce thetransmission power control margin of error.

[0185] Furthermore, it is also possible in the third embodiment toprepare the memory sizes shown in FIG. 2, and control interleaving ofbit units across multiple frames in the compressed mode. In this case,as in the first embodiment described above, it is possible to secure anappropriate interleaving time in the compressed mode, as in the normalmode, and to further reduce transmission errors resulting frominterleaving in bit units.

[0186] In the embodiments one to three described above, the frame timingwas changed in the normal mode and the compressed mode, but the presentinvention is not restricted to this, and it is acceptable tointermittently transmit with the same frame timing in compressed modeand normal mode, as in a fourth embodiment of the present inventiondescribed below.

[0187] Firstly, the constitution of the CDMA system will be explained.FIG. 15 is a block diagram showing a CDMA system according to the fourthembodiment of the present invention. The CDMA system comprises atransmitter 13 and a receiver 2B. Such a CDMA system is provided withboth base station and mobile stations. The base station and the mobilestations carry out radio communication using a CDMA communicationmethod.

[0188] The transmitter 1B, as shown in FIG. 15, comprises a controller11B, an error-correction encoder 12, an interleaver 13, aframing/spreading unit 14B, a radio frequency transmitter 15, etc.Through negotiations with the receiver 2B, the controller 11B mainlycontrols the operations of the interleaver 13, the framing/spreadingunit 14B, and the radio frequency transmitter 15. In compressed mode,this controller 11B instructs to the framing/spreading unit 14Bmulti-code transmission for multiple frames to be code-multiplexed andtransmission timings for transmitting compressed mode frames.

[0189] The error-correction encoder 12, the interleaver 13, and theradio frequency transmitter 15 are the same as in the first embodimentalready described above, and explanation thereof will be omitted. Asregards the interleaver 13, it has a memory for interleaving one frame.

[0190] The framing/spreading unit 14B spreads the band in correspondencewith normal mode and compressed mode, using a spreading code for eachuser, and forms a frame corresponding to each mode. When the controller11B has instructed transmission timing in correspondence with each ofthe modes, the framing/spreading unit 14B sends the frame to the radiofrequency transmitter 15 in accordance with the instructed transmissiontiming. Furthermore, in the compressed mode, the framing/spreading unit14B receives a command for multi-code transmission from the controller11B, and code-multiplexes two post-interleave frames in accordance withthat command.

[0191] In order to code-multiplex two frames, the framing/spreading unit14B has a one-frame memory. That is, the interleaver 13 and theframing/spreading unit 14B each comprise a one-frame memory, enablingtwo frames to be code-multiplexed using a total memory size equivalentto two frames.

[0192] The receiver 23, as shown in FIG. 15, comprises a controller 21B,an error-correction decoder 22, a deinterleaver 23, adeframing/de-spreading unit 24B, a radio frequency receiver 25, etc.Through negotiations with the transmitter 1B, the controller 21B mainlycontrols the operations of the deinterleaver 23 and thedeframing/de-spreading unit 24B. In the compressed mode, this controller21B instructs the deframing/de-spreading unit 24B of reception timingsfor receiving multi-code transmission and compressed mode frames.

[0193] The error-correction decoder 22, the deinterleaver 23, and theradio frequency transmitter 25 are the same as in the first embodimentalready described above, and explanation thereof will be omitted. Asregards the deinterleaver 23, it has a memory for interleaving oneframe.

[0194] Like the framing/spreading unit 14B described above, thedeframing/de-spreading unit 24B comprises a one-frame memory fordeframing. When the controller 21B has instructed a reception timing incorrespondence with each of the modes, the deframing/de-spreading unit24B extracts the reception signal from the radio frequency transmitterin accordance with that reception timing. Furthermore, in the compressedmode, the deframing/de-spreading unit 24B receives a command formulti-code transmission from the controller 21B, separates the de-spreaddata into frame units in accordance with that command, and outputs theframes in sequence to the deinterleaver 23.

[0195] Next, the primary constitution of the framing/spreading unit 143and the deframing/de-spreading unit 24B will be explained. FIG. 16 is adiagram explaining memory distribution of the framing/spreading unit 14Baccording to the fourth embodiment, wherein FIG. 16(a) illustrates thearea used in normal mode, and FIG. 16(b) illustrates the area used incompressed mode. In FIG. 16, the framing/spreading unit 14B has a memory141A. The deframing/de-spreading unit 24B also has a memory of the samememory size as that of the framing/spreading unit 14B.

[0196] In the fourth embodiment, since code-multiplexing is performedacross two frames in the compressed mode, a one-frame memory size, incorrespondence with a two-frame code-multiplexing size, is set in theboth framing/spreading unit 14B and the deframing/de-spreading unit 24B.In fact, two-frame framing and deframing can be achieved using theone-frame memories of the interleaver 13 the deinterleaver 23.

[0197] In normal mode (see FIG. 16(a)), since code-multiplexing is notneeded, framing and the like is carried out based on data interleaved bythe interleaver 13 without using the memory 141A. On the contrary, incompressed mode (see FIG. 16(b)), a two-frame memory size is required toperform code-multiplexing, and therefore the memory 141A of theframing/spreading unit 14B is used in addition to the memory of theinterleaver 13. Similarly, whether the memory is used or not in thedeframing/de-spreading unit 24B also varies depending on the mode.

[0198] Next, frame transmission including compressed mode will beexplained. FIG. 17 is a diagram explaining frame transmission of adownlink according to the fourth embodiment. In FIG. 17, the verticalaxis represents transmission rate/transmission power, and the horizontalaxis represents time. Furthermore, in FIG. 17, F represents one frame.In the CDMA system, during normal transmission, a period of time isprovided to slot the frame and transmit it intermittently, and thestrength of other frequency carriers is measured using the fact that aframe is not transmitted during that period.

[0199] For this purpose, the slotted frame must be compressed, and inconventional methods, the transmission duration of a compressed framebecomes half of the normal transmission duration. In this case, ifinterleaving is performed in the same manner as in normal transmission,there will only be half of the necessary interleaving time, making itimpossible to achieve adequate interleaving effects.

[0200] Accordingly, the transmitter 1B performs interleaving of the samesize as in the normal mode, and code-multiplexes multiple frames in theframe timing, in order to secure the same timing for interleaving in thecompressed mode as in the normal mode, in compressed mode. For instance,in the example shown in FIG. 17, in normal transmission (normal mode),post-interleaving frames are transmitted in a sequence of frames #1, #2,and thereafter, in slotted transmission (compressed mode), individuallyinterleaved frames #3 and #4 are code-multiplexed together, andcompressed frames are transmitted.

[0201] Next, the operation will be explained. Since the transmission andreception is performed in the same manner as the conventional methods,explanation thereof will be omitted. Firstly, the transmission operationof the transmitter 1B will be explained. FIG. 18 is a flowchartexplaining the transmission operation in compressed mode. The executionof the operation of FIG. 18 is controlled by the controller 11B althoughindividual operations are performed by various sections. In thecompressed mode, interleaving in one frame is instructed to theinterleaver 13 (Step S401), and the interleaver 13 interleaves in oneframe.

[0202] Then, when the time reaches a given frame timing for multi-codetransmission (Step S402), multi-code transmission and transmissiontimings are instructed to the framing/spreading unit 14B (Step S403).Consequently, the framing/spreading unit 14B code-multiplexes twoframes. In this way, in the compressed mode, frames are transmittedintermittently (non-continuously).

[0203] Next, the reception operation of the receiver 2B will beexplained. FIG. 19 is a flowchart explaining the reception operation inthe compressed mode. The execution of the operation of FIG. 19 iscontrolled by the controller 21B although individual operations areperformed by various sections. In the compressed mode, when the timereaches the frame timing for the multi-code transmits son describedabove (Step S411), frame separation of received code-multiplexed dataand a reception timing are instructed to the deframing/de-spreading unit24B (Step S412).

[0204] Then, deinterleaving in the separated frames is instructed to thedeinterleaver 23 (Step S413), and the deinterleaver 23 deinterleaves oneframe. In this way, in the compressed mode, frames are receivedintermittently (non-continuously).

[0205] As described above, according to the fourth embodiment, in thecompressed mode, multiple frames which have been interleaved in bitunits to minimize the effects of transmission errors are compressed bycode division multiplexing in the given frame timing prior totransmission. Therefore, it is possible to secure an appropriateinterleaving time in the same way and using the same constitution in thecompressed mode and the normal mode. In this way, by controlling ON/OFFin each compressed mode frame, poor performance caused by interleavingin bit units can be prevented.

[0206] Furthermore, since the memory size used corresponds to the numberof frames to be code-multiplexed in the compressed mode,code-multiplexing can be performed reliably and without loss in thecompressed mode.

[0207] Furthermore, it is also possible in the fourth embodiment tocontrol interleaving of bit units across multiple frames in thecompressed mode in the way as the first embodiment described above. Inthis case, it is possible to secure a longer time for interleaving byincreasing the size of the memories of the interleaver and thedeinterleaver in compressed mode than in the normal mode. As aconsequence, transmission errors resulting from interleaving in bitunits can be reduced. In particular, when code-multiplexed frames areinterleaved by replacing other frames, places where multiplecode-multiplexed frames are in error can be dispersed, improving thecorrecting result of the error-correction coding.

[0208] In the embodiments 1 to 4 described above, transmission power isincreased in order to transmit frames in the compressed mode withoutinformation loss, but the present invention is not restricted to this,and it is acceptable to determine the amount of the transmission powerafter considering interference on other user channels caused by theamount of the transmission power, as described below in a fifthembodiment.

[0209] Firstly, the constitution of the CDMA system will be explained.FIG. 20 is a block diagram showing a CDMA system according to a fifthembodiment of the present invention. The CDMA system comprises atransmitter 1C and a receiver 2C. Such a CDMA system is provided withboth base station and mobile stations. The base station and the mobilestations carry out radio communication using a CDMA communicationmethod.

[0210] As shown in FIG. 20, the transmitter 1C comprises a controller11C, an error-correction encoder 12, an interleaver 13, aframing/spreading unit 14C, a radio frequency transmitter 15, etc.Through negotiations with the receiver 2C, the controller 11C mainlycontrols the operations of the interleaver 13, the framing/spreadingunit 14C, and the radio frequency transmitter 15. In compressed mode,this controller 11C instructs to the framing/spreading unit 14C areduction of information rate and transmission timings for transmittingcompressed mode frames. Furthermore, this controller 11C differs fromthe one in embodiments 1 to 4 described above in that it does notgenerate a command to the radio frequency transmitter 15 to raise thetransmission power in the compressed mode.

[0211] The error-correction encoder 12, the interleaver 13, and theradio frequency transmitter 15 are the same as in the first embodimentalready described above, and explanation thereof will be omitted. Asregards the interleaver 13, it has a memory for interleaving one frame.

[0212] The framing/spreading unit 14C spreads the band in correspondencewith normal mode and compressed mode, using a spreading code for eachuser, and forms a frame corresponding to each mode. When the controller11C has instructed a transmission timing in correspondence with each ofthe mode, the framing/spreading unit 14C sends the frame to the radiofrequency transmitter 15 in accordance with that transmission timing.Furthermore, in the compressed mode, when the framing/spreading unit 14Creceive a command to reduce the information rate from the controller 11Cthen it compresses the insufficiently interleaved frame to form acompressed mode frame in compliance with that command.

[0213] As shown in FIG. 20, the receiver 2C comprises a controller 21C,an error-correction decoder 22, a deinterleaver 23, adeframing/de-spreading unit 24C, a radio frequency transmitter 25, etc.Through negotiations with the transmitter 1C, the controller 21C mainlycontrols the operations of the deinterleaver 23 and thedeframing/de-spreading unit 24C. In the compressed mode, this controller21C instructs to the deframing/de-spreading unit 24C a reduction ininformation rate and reception timings for receiving compressed modeframes.

[0214] The error-correction decoder 22, the deinterleaver 23, and theradio frequency transmitter 25 are the same as in the first embodimentalready described above, and explanation thereof will be omitted. Asregards the deinterleaver 23, it has a memory for interleaving oneframe.

[0215] When the controller 21C has instructed a reception timing incorrespondence with each of the modes, the deframing/de-spreading unit24C extracts the received signal from the radio frequency transmitter 25in accordance with that reception timing. Furthermore, in the compressedmode, when the deframing/de-spreading unit 24C receives a command toreduce information rate from the controller 21C then it lowers theinformation rate in accordance with that command, performs framing andde-spreading, and outputs the frames in sequence to the deinterleaver23.

[0216] Next, frame transmission including compressed mode will beexplained. FIG. 21 is a diagram explaining frame transmission of adownlink according to the fifth embodiment. In FIG. 21, the verticalaxis represents transmission rate/transmission power, and the horizontalaxis represents time. In the CDMA system, during normal transmission, aperiod of time is provided to slot the frame and transmit itintermittently, and the strength of other frequency carriers is measuredusing the fact that a frame is not transmitted during that period. Forthat purpose, the slotted frame must be compressed, and in aconventional method, the transmission power is increased whentransmitting the compressed frame. In this case, amount of interferencepower to other user channels increases, leading to deterioration intransmission.

[0217] Accordingly, as shown in FIG. 21, when the same transmissionpower is secured in the compressed mode as in the normal mode, loweringthe transmission rate by a corresponding amount, and an interleavedtransmission frame is sent across multiple compressed mode frames, it ispossible to realize a handover between frequencies with reducedinterference.

[0218] Next, the operation will be explained. Since the transmission andreception is performed in the same manner as the conventional methods,explanation thereof will be omitted. Firstly, the transmission operationof the transmitter 1C will be explained. FIG. 22 is a flowchartexplaining the transmission operation in the compressed mode. Theexecution of the operation of FIG. 22 is controlled by the controller11C although the individual operations are performed by varioussections. In the compressed mode, interleaving in one frame isinstructed to the interleaver 13 (Seep S501), and the interleaver 13interleaves in one frame.

[0219] Then, when the time reaches the compressed mode frame timing(Step S502), reduction of transmission rate and a transmission timingare instructed to the framing/spreading unit 14C (Step S503).Consequently, the frame is transmitted at a lower transmission rate inthe compressed mode time. In this way, in the compressed mode, framesare transmitted intermittently (non-continuously).

[0220] Next, the reception operation of the receiver 2C will beexplained. FIG. 23 is a flowchart explaining the reception operation inthe compressed mode. The execution of the operation of FIG. 23 iscontrolled by the controller 21C although the individual operations areperformed by various sections. In the compressed mode, when the timereaches the compressed mode frame timing (Step S511), a reduction oftransmission rate and a reception timing are instructed to thedeframing/de-spreading unit 24C (Step S512).

[0221] Then, deinterleaving in the one frame instructed to thedeintenleaver 23 (Step S513), and the deinterleaver 23 deinterleaves oneframe. In this way, in the compressed mode, frames are receivedintermittently (non-continuously).

[0222] As described above, according to the fifth embodiment, in thecompressed mode, compressed frames are intermittently transmitted at atransmission rate which is lower than the transmission rate in thenormal mode while using the same transmission power as in the normalmode. Therefore, during the frequency handover, the amount ofinterference power to other users on the same frequency is reduced.Consequently, it is possible to realize a handover between frequencieswith less interference.

[0223] Furthermore, in the fifth embodiment, in the compressed mode, acompressed frame may be divided into the front and rear of the sameframe timing as in the normal mode, and transmitted intermittently incompliance with that arrangement, as in the second embodiment describedabove. Because of this fact, it is possible to secure an appropriateinterleaving time in compressed mode in the same way as in the normalmode, with a simple interleave constitution. As a result, poorperformance caused by interleaving in bit units can be prevented.

[0224] Furthermore, in the fifth embodiment, in the compressed mode, acompressed frame may be slotted and transmitted intermittently in N slotunits in the same manner as in the third embodiment described above.Because of this fact, it is possible to receive transmission powercontrol bits transmitted in the downlink in comparatively short timeintervals. As a result, the amount of error in the transmission powercontrol can be reduced.

[0225] In the fifth embodiment described above, one frame wasinterleaved, but the present invention is not restricted to this, and itis acceptable to prevent compression in the interleaving time byinterleaving across multiple frames. With the exception of increase thememory size of the interleaver, as in the first embodiment, the sixthembodiment has the same overall constitution as the fifth embodimentdescribed above, and so only the differing aspects of the operation willbe explained below.

[0226] Accordingly, frame transmission including compressed mode will beexplained. FIG. 24 is a diagram explaining frame transmission of adownlink according to the sixth embodiment. In FIG. 24, the verticalaxis represents transmission rate/transmission power, and the horizontalaxis represents time. The difference with the fifth embodiment describedabove is that, as shown in FIG. 24, the interleaving is carried outacross multiple frames, i.e. two frames if the compressed mode frame isa ½ frame. Consequently, deterioration of decoding caused by compressingthe interleaving time can be reduced.

[0227] Next, the operation will be explained. Since the transmission andreception is performed in the same manner as in the conventionalmethods, explanation thereof will be omitted. Firstly, the transmissionoperation of the transmitter of the sixth embodiment will be explained.FIG. 25 is a flowchart explaining the transmission operation in thecompressed mode. The execution of the operation of FIG. 25 is controlledby the controller 11C although the individual operations are performedby various sections. In the compressed mode, interleaving across twoframes is instructed to the interleaver 13 (Step S601), and theinterleaver 13 interleaves two frames.

[0228] Then, when the time reaches the compressed mode frame timing(Step S602), reduction of transmission rate and a transmission timingare instructed to the framing/spreading unit 140 (Step S603).Consequently, the frame is transmitted at a lower transmission rate inthe compressed mode time. In this way, in the compressed mode, framesare transmitted intermittently (non-continuously).

[0229] Next, the reception operation according to the receiver of thesixth embodiment will be explained. FIG. 26 is a flowchart explaining areception operation in the compressed mode. The execution of theoperation of FIG. 26 is controlled by the controller 21C although theindividual operations are performed by various sections. In thecompressed mode, when the time reaches the compressed mode frame timing(Step S611), a reduction of transmission rate and a reception timing areinstructed to the deframing/despreading unit 24C (Step S612).

[0230] Then, deinterleave across two frames is instructed to thedeinterleaver 23 (Step S613), and the deinterleaver 23 deinterleavesacross two frames. In this way, in the compressed mode, frames arereceived intermittently (non-continuously).

[0231] As described above, according to the sixth embodiment, inadaition to what has been described in the fifth embodiment describedabove, in the compressed mode, bit units are interleaved across multipleframes, enabling an appropriate interleaving time to be secured in thecompressed mode as in the normal mode. As a consequence, transmissionerrors caused by interleaving of bit units can be further reduced.

[0232] Furthermore, in the sixth embodiment, in the compressed mode, acompressed frame may be divided into the front and rear of the sameframe timing as in the normal mode, and transmitted intermittently incompliance with that arrangement in the same manner as in the secondembodiment described above. Because of this fact, it is possible tosecure an appropriate interleaving time in compressed mode in the sameway as in the normal mode, with a simple interleaving constitution. As aresult, poor performance caused by interleaving in bit units can beprevented.

[0233] Furthermore, in the sixth embodiment, in the compressed mode, acompressed frame may be slotted and transmitted intermittently in N slotunits in the same manner as in the third embodiment described above.Because of this fact, it is possible to receive transmission powercontrol bits transmitted in the downlink in comparatively short timeintervals. As a result, the amount of error in the transmission powercontrol can be reduced.

[0234] In the above-mentioned embodiments 1 to 6, a function orpreventing transmission deterioration in the compressed mode wasexplained, but the present invention is not restricted to this, and itis acceptable to vary the amount of transmission power duringtransmission power control as in a seventh embodiment described below.

[0235] Firstly, the constitution of the CDMA system will be explained.FIG. 27 is a block diagram showing a CDMA system according to a seventhembodiment of the present invention. The CDMA system comprises atransmitter 1D and a receiver 2D. Such a CDMA system is provided withboth the base station and mobile stations. The base station and themobile stations carry out radio communication using a CDMA communicationmethod.

[0236] As shown in FIG. 27, the transmitter 1D comprises a controller11D, an error-correction encoder 12, an interleaver 13, aframing/spreading unit 14D, a radio frequency transmitter 15, etc.Through negotiations with the receiver 2D, the controller 11D mainlycontrols the operations of the interleaver 13, the framing/spreadingunit 14D, and the radio frequency transmitter 15. This controller 11Dsupplies compressed mode information such as transmission timings incompressed mode to the framing/spreading unit 14D. Furthermore, thiscontroller 14D instructs increase or decrease of the transmission powerto the radio frequency transmitter 15, based on received powerinformation and TPC bit information received from the receiver 2D via anuplink.

[0237] The error-correction encoder 12, the interleaver 13, and theradio frequency, transmitter 15 are the same as in the first embodimentalready described above, and explanation thereof will be omitted. Asregards the interleaver 13, it has a memory for interleaving one frame.Furthermore, the radio frequency transmitter 15 increase or decreasesthe transmission power in accordance with the transmission powerincrease or decrease instruction of the controller 11D, and outputs thetransmission signals.

[0238] The framing/spreading unit 14D is assigned operations such asspreading the band in correspondence with the normal mode and compressedmode, using a spreading code for each user, forming a framecorresponding to each mode, and, when the controller 11D has instructeda transmission timing in correspondence with each of the modes, sendingthe frame to the radio frequency transmitter 15 in accordance with thattransmission timing.

[0239] As shown in FIG. 27, the receiver 2D comprises a controller 21D,an error-correction decoder 22, deinterleaver 23, adeframing/de-spreading unit 24D, a radio frequency transmitter 25, etc.Through negotiations with the transmitter 1D, the controller 21D mainlycontrols the operations of the deinterleaver 23 and thedeframing/de-spreading unit 24D. In the compressed mode, this controller21D supplies compressed frame information, such as reception timings andthe like for receiving compressed mode frames, to thedeframing/de-spreading unit 24D.

[0240] The error-correction decoder 22, the deinterleaver 23, and theradio frequency transmitter 25 are the same as in the first embodimentalready described above, and explanation thereof will be omitted. Here,the deinterleaver 23 has a memory for interleaving one frame.Furthermore, when the radio frequency receiver 25 has received areception signal, it notifies the controller 21D of information(information on reception power) showing the reception power.

[0241] When the deframing/de-spreading unit 243 has received receptiontimings in correspondence with each of the modes from the controller21D, it extracts the reception signal from the radio frequencytransmitter 25 in accordance with the reception timings. Furthermore, inthe compressed mode, this deframing/de-spreading unit 24D receivescompressed frame information from the controller 21D and performsdeframing and de-spreading, and sequentially outputs the frames to thedeinterleaver 23. Furthermore, the deframing/de-spreading unit 24Ddetects TPC bits from the received signal, and notifies the controller21D of these.

[0242] Next, the relationship between the TPC bits and the transmissionpower control amount will be explained. FIG. 28 is a diagram showing therelationship between transmission power control symbols and transmissionpower control amounts according to the seventh embodiment. The tableshown in FIG. 28 is held by the controller 11D of the transmitter 1D andalso the controller 21D of the receiver 2D. The TPC bit is thetransmission power control symbol, and since it comprises one bit, ithas two states: 1 (ON) and 0 (OFF). In the normal mode, a transmissionpower control amount of +1.0 dB (decibel) is applied in the 1 (ON) stateand a transmission power control amount of −1.0 dB is applied in the 0(OFF) state. That is, the unit of transmission power control in thenormal mode is 1 dB.

[0243] On the other hand, in the compressed mode, a transmission powercontrol amount of +3.0 dB (decibels) is applied in the 1 (ON) state, anda transmission power control amount of −3.0 dB is applied an the 0 (OFF)state. That is, the unit of transmission power control in the normalmode is 3 dB. The transmission power control unit used in the compressedmode has a greater absolute value than that used in the normal mode, forthe reason that idle period (non-transmission timing) in the compressedmode lowers the adhesion capability to the transmission power control.

[0244] Next, the operation will be explained. The seventh embodimentdiffers from the other embodiments in respect of its transmission powercontrol function, and therefore only the transmission power control willbe explained. FIG. 29 is a flowchart explaining the transmission powercontrol operation in compressed mode according to the seventhembodiment. Transmission power control of the transmitter 1D and thereceiver 2D explained here is the transmission power control to anuplink.

[0245] A TPC bit from the receiver 2D and reception power information onthe receiver 2D side are sent to the transmitter 1D. In the transmitter1D, when the TPC bit and the reception power information are received(Step S701), transmission power increase/decrease information isdetermined based on this received information (Step S702). Then,transmission from the radio frequency transmitter 15 is controlled atthat determined transmission power (Step S703).

[0246] More specifically, for instance, when there is one TPC bit, aninstruction is made to increase the transmission power, and consequentlythe transmission power control of +3 dB from the table of FIG. 28 isset. Therefore, an instruction to transmit after raising the presenttransmission power by 3 dB is sent to the radio frequency transmitter15. On the other hand, when the TPC bit is 0, an instruction is given todecrease the transmission power, by setting the transmission powercontrol of −3 dB from the table of FIG. 28. Therefore, an instruction totransmit after decreasing the present transmission power by 3 dB is sentto the radio frequency transmitter 15.

[0247] As described above, according to the seventh embodiment, in thecompressed mode, transmission power is controlled so that thetransmission power control unit for one transmission is greater than inthe normal mode, and consequently, even when the temporal intervals ofthe transmission power control during intermittent transmission arewider, it is possible to widen the control range of the transmissionpower and maintain adhesion to the transmission power in the compressedmode. As a consequence, the amount of error of transmission powercontrol in the compressed mode can be reduced.

[0248] Furthermore, in the seventh embodiment, in the compressed mode, acompressed frame may be slotted and transmitted intermittently in N slotunits in the same manner as in the third embodiment described above.Consequently, it is possible to transmit transmission power control bitsin the downlink in comparatively short time intervals. As a result, theamount of error in the transmission power control can be reduced.

[0249] In the above-mentioned seventh embodiment, the TPC bit stateswere limited to two types of increase and decrease, but the presentinvention is not restricted to this, and it is acceptable to vary theamount of transmission power control for each mode, as in an eighthembodiment explained below. The eighth embodiment has the same overallconstitution as the seventh embodiment described above, and so only thediffering aspects of the operation will be explained below. In thefollowing explanation, the reference numerals of FIG. 27 will be used.

[0250] Firstly, the relationship between the TPC bits and thetransmission power control amount will be explained. FIG. 30 is adiagram showing the relationship between transmission power controlsymbols and transmission power control amounts according to the eighthembodiment. The table shown in FIG. 30 is held by the controller 11D ofthe transmitter 1D and also the controller 21D of the receiver 2D.

[0251] In the eighth embodiment, the TPC bit is the transmission powercontrol symbol, and there are two bits. Therefore, there are four typesof states: (11B (B represents a binary number), 10B, 01B, and 00B). Thetwo TPC bit states 11B and 10B represent an increase of transmissionpower, and the two TPC bit states 01B and 00B represent a decrease oftransmission power.

[0252] In the normal mode, as in the seventh embodiment described above,there are only two types of states, ON and OFF. However, since two TPCbits are used, ON is 11B and OFF as 00B. When the TPC bits are 11B thetransmission power control amount is +1 dB, and when they are 00B thetransmission power control amount is −1 dB. Similarly, in the compressedmode, as in the seventh embodiment described above, when the TPC bitsare 11B the transmission power control amount is increased by threetimes the transmission power control amount in the normal mode, namely+3 dB. When the TPC bits are 00B the transmission power control amountis increased by three times of the transmission power control amount inthe normal mode, namely −3 dB. In the eighth embodiment, four types ofvariation are applied to the transmission power control amount in thecompressed mode, so that when the TPC bits are 10B the transmissionpower control amount is +1 dB, and when they are 01B the transmissionpower control amount is −1 dB.

[0253] In the normal mode, when the TPC bits are in the 11B state, atransmission power control amount of +1.0 dB (decibels) is applied, andin the 00B state, a transmission power control amount of −1.0 dB isapplied. That is, the unit of transmission power control in the normalmode is 1 dB. In the normal mode, there are no stipulations concerningthe state 10B and the state 10B, and the transmission power remains inits current state during this mode.

[0254] On the other hand, in the compressed mode, when the TPC bits are11B, a transmission power control amount of +3.0 dB (decibels) isapplied, and when the TPC bits are 00B, a transmission power controlamount of −3.0 dB is applied. That is, when the TPC bits are at 11B or00B, the unit of transmission power control in the normal mode is 3 dB.

[0255] Furthermore, in the compressed mode, when the TPC bits are 10B, atransmission power control amount of +1.0 dB (decibel) is applied, andwhen the TPC bits are 01B, a transmission power control amount of −1.0dB is applied. That is, when the TPC bits are at 10B or 01B, the unit oftransmission power control in the compressed mode is 1 dB.

[0256] Thus, the transmission power control unit is varied in thecompressed mode in order to improve the adhesion capability of thetransmission power control, making it possible to appropriatelyaccommodate changes in the idle period (non-transmission timing) in thecompressed mode.

[0257] Next, the operation will be explained. The eighth embodimentdiffers from the other embodiments in respect of its transmission powercontrol function, and therefore only the transmission power control willbe explained. FIG. 31 is a flowchart explaining the transmission powercontrol operation in compressed mode according to the eighth embodiment.Transmission power control of the transmitter 1D and the receiver 2Dexplained here is the transmission power control to an uplink.

[0258] A TPC bit from the receiver 2D and reception power information onthe receiver 2D side are sent to the transmitter 1D. When thetransmitter 1D receives the TPC bit and the reception power information(Step S901) it determines the value of the TPC bits (Step S802). Then,the table of FIG. 30 is consulted, and a desired transmission powerincrease/decrease information is set, based on the determination in theStep S802 (Step S803). Then, transmission to the radio frequencytransmitter 15 is controlled at the set transmission power (Step S804).

[0259] More specifically, for instance, when the TPC bits are 11B, aninstruction is made to increase the transmission power, and thetransmission power control of +3 dB from the above-mentioned table ofFIG. 30 is set. Therefore, an instruction to transmit after raising thepresent transmission power by 3 dB is sent to the radio frequencytransmitter 15. On the other hand, when the TPC bits are 00B, aninstruction is given to decrease the transmission power, by setting thetransmission power control of −3 dB from the table of theabove-mentioned FIG. 30. Therefore, an instruction to transmit afterdecreasing the present transmission power by 3 dB is sent to the radiofrequency transmitter 15.

[0260] Furthermore, when the TPC bits are 10B, an instruction is made toincrease the transmission power, and the transmission power control of+1 dB from the above-mentioned table of FIG. 30 is set. Therefore, aninstruction to transmit after raising the present transmission power by1 dB is sent to the radio frequency transmitter 15. On the other hand,when the TPC bits are 01B, an instruction is given to decrease thetransmission power, by setting the transmission power control of −1 dBfrom the table of the above-mentioned FIG. 30. Therefore, an instructionto transmit after decreasing the present transmission power by 1 dB issent to the radio frequency transmitter 15.

[0261] As described above, according to the eighth embodiment,transmission power is controlled in compliance with transmission powercontrol units in correspondence with the normal mode and the compressedmode, and in addition, in correspondence with the temporal intervals ofthe transmission power control in the compressed mode. Therefore, in thecompressed mode, even when the temporal intervals of the transmissionpower control fluctuate and become long during intermittenttransmission, it is possible to use an appropriate transmission powercontrol range, and thereby maintain adhesion to the transmission power.As a consequence, the amount of error of transmission power control inthe compressed mode can be reduced.

[0262] The number of TPC bits and the transmission power is greater thanthe seventh embodiment described above. However, transmission power isin any case greater in compressed mode so that the needed transmissionpower of the TPC bit is attained by that greater power. Consequently,there is a merit that the transmission error rate has almost no effecton the control performance.

[0263] Furthermore, in the eighth embodiment, in the compressed mode, acompressed frame may be slotted and transmitted intermittently in N slotunits in the same manner as in the third embodiment described above.Consequently, it is possible to receive transmission power control bitstransmitted in the downlink in comparatively short time intervals. As aresult, the amount of error in the transmission power control can bereduced.

[0264] In the embodiments 1 to 8 explained above, the transmissionformat in the compressed mode has a constitution for maintaininginterleaving performance and transmission power control precision, butthe present invention is not restricted to this, and it is acceptable toset the transmission formation in consideration of reducing the numberof spreading codes used, as in the following ninth embodiment.

[0265] Firstly, the constitution of a base station in which the CDMAsystem of a ninth embodiment of the present invention has been appliedwill be explained. The constitution of the mobile stations will be notexplained here. FIG. 32 is a block diagram showing an exampleconstitution of a base station according to the ninth embodiment of thepresent invention. As shown in FIG. 32, this base station comprises atransmitter group 100, an adder 110, a radio frequency transmitter 120,a compressed mode controller 200 which is connected to the transmittergroup 100 and controls transmission in the compressed mode, etc. Radiocommunication between the base station and mobile stations not shown inthe diagram are performed using the CDMA communication method.

[0266] The transmitter group 100 comprises multiple transmitters #1 to#M (where M is a natural number) for creating transmission dataseparately for users in correspondence with a serviceable number ofusers. Each of the transmitters #1 to #M has the same constitution. Theconstitution will be explained taking the transmitter #1 as an example.As shown in FIG. 32, the transmitter #1 comprises a controller 11E, theerror-correction encoder 12, the interleaver 13, a framing/spreadingunit 14E, a transmission power control amplifier 16, etc.

[0267] Through negotiations with the compressed mode controller 200, thecontroller 11E mainly controls the operations of the interleaver 13, theframing/spreading unit 14E, and the transmission power control amplifier16. In the compressed mode, the controller 11E supplies transmissiontimings for transmitting compressed mode frames, and spreading codeshaving a lower spreading factor than those normally used fortransmitting compressed mode frames, to the framing/spreading unit 14E.

[0268] The error-correction encoder 12 and the interleaver 13 are thesame as in the first embodiment already described above, and explanationthereof will be omitted. As regards the interleaver 13, it has a memoryfor interleaving one frame.

[0269] The framing/spreading unit 14E spreads the band using spreadingcodes of different spreading factors in correspondence with the normalmode and the compressed mode, and forms a frame for each mode. When thecontroller 11E has instructed transmission timings in correspondencewith each of the modes, the framing/spreading unit 14E sends the framesto the transmission power control amplifier 16 in accordance with thetransmission timing. Furthermore, in the compressed mode, thisframing/spreading unit 14E receives an instruction from the controller11E to lower the spreading factor, and in accordance with thatinstruction it obtains a transmission signal using a lower spreadingfactor than in the normal mode.

[0270] In compliance with the control of the controller 11E, thetransmission power control amplifier 16 amplifies the averagetransmission power of the transmission signal, obtained by theframing/spreading unit 14E, in the compressed mode as compared with thenormal mode, and outputs the transmission signal. The transmitters #1 to#M independently determine whether or not to use compressed modetransmission, and furthermore, since the ratio of compression in thecompressed mode is set independently by the individual transmitters #1to #M, transmission power control amplifiers 16 are providedindependently to the individual transmitters #1 to #M.

[0271] The adder 110 adds the transmission signals outputted from thetransmitters #1 to #M comprising the transmitter group 100, and sendsthem to the radio frequency transmitter 120 provided in thelatter-stage. The radio frequency transmitter 120 converts the signaloutput obtained by the adder 110 to a radio frequency, and transmits it.One radio frequency transmitter 120 is provided in each base station.

[0272] As shown in FIG. 32, the compressed mode controller 220 comprisesa compressed mode manager 201, a frame combination controller 202, aspreading code allocation controller 203, a transmission timingcontroller 204, etc. The compressed mode manager 201 manages thecompressed mode of each transmitter in the transmitter group 100, andinputs/outputs control data for to the compressed mode.

[0273] The frame combination controller 202 receives transmission periodinformation about compressed mode frames of transmitters performingcompressed mode transmission from the compressed mode manager 201. Incompliance with that transmission period information, the framecombination controller 202 searches among the multiple compressed modeframes for a combination of frames having a total transmission timingwhich is within one frame duration.

[0274] The spreading code allocation controller 203 allocates aspreading code, to be used for spreading a compressed mode frame, totransmitters transmitting in the compressed mode. The transmissiontiming controller 204 controls the timings at which compressed modeframes are to be transmitted in the compressed mode.

[0275] Next, frame transmission including compressed mode will beexplained. FIG. 33 is a diagram explaining frame transmission of adownlink according to the ninth embodiment. In FIG. 33, the verticalaxis represents transmission rate/transmission power, and the horizontalaxis represents time. In the CDMA system, during normal transmission, aperiod of time is provided to slot the frame and transmit itintermittently, and the strength of the other frequency carriers ismeasured using the fact that the frames are not transmitted (idleperiod) during that period.

[0276] For that purpose, the slotted frame must be compressed, and in aconventional method, the spreading factor is decreased when transmittingthe compressed frame. In this case, a smaller number of spreading codeshaving a lower spreading factor must be allocated to each user carryingout compressed mode transmission, consuming valuable spreading coderesources.

[0277] Accordingly, as shown in FIG. 33, for instance during compressedmode transmission between the base station of FIG. 32 and mobilestations M1 and M2, a group of compressed mode frames is collected fromamong the compressed mode frames created by multiple users in such a waythat the collected group has a total transmission period of less thanone frame duration. The same spreading code having a low spreadingfactor is allocated to each frame in the group, and they are transmittedat times which do not overlap within one frame duration, therebyenabling multiple mobile stations to share one spreading code. That is,in the downlink for the mobile stations M1 and M2, different spreadingcodes A and B are fixedly allocated to the mobile stations M1 and M2during the normal mode normal transmission).

[0278] On the contrary, in the compressed mode (slotted transmission),an identical spreading code C is allocated to both of the mobilestations M1 and M2, and compressed mode frame transmission timings ofthe mobile stations M1 and M2 are controlled so that their transmissiontimings which both use the spreading code C do not overlap, enabling thecompressed mode frame of each to be transmitted during the idle periodT2 or T1 of the other.

[0279] Next, the operation will be explained. Firstly, the operation ofthe framing/spreading unit 14E during he compressed mode in thetransmitters #1 to #M will be explained. FIG. 34 is a flowchartexplaining the transmission operation in the compressed node accordingto the ninth embodiment of the present invention. The execution of theoperation of FIG. 34 is controlled by the controller 11E although theindividual operations are performed by various sections. In thecompressed mode, interleaving in one frame is instructed to theinterleaver 13 (Step S901), and the interleaver 13 interleaves oneframe. Then, information relating to the compressed mode frame is outputto the compressed mode controller 200 (Step S902).

[0280] Then, a negotiation is carried out with the compressed modecontroller 200, and a spreading factor (spreading code) instruction ofthe compressed mode controller 200 and a compressed mode frametransmission timing are supplied to the framing/spreading unit 14E (StepS903). Moreover, the transmission power control amplifier 16 isinstructed to increase the average transmission power (Step S904), andthe compressed mode frame is transmitted at a high transmission power.In this way, frames are transmitted intermittently (non-continuously) inthe compressed mode.

[0281] Next, the control operation in compressed mode of the compressedmode controller 200 will be explained. FIG. 35 is a flowchart explainingthe compressed mode control operation according to the ninth embodiment.The operation of FIG. 35 is controlled by the compressed mode manager201 although the individual operations are performed by various sectionsin the compressed mode controller 200. In FIG. 35, information relatingto compressed mode is gathered through communication between thetransmitters #1 to #M.

[0282] Accordingly, the channels are checked to determine whether theyare in the compressed mode (Step S911). Then, when it has been confirmedthat there are multiple channels in the compressed mode (Step S912), thetransmission period of the compressed mode frame in each channel incompressed mode is checked (Step S913). On the other hand, if there areno multiple channels in the compressed mode in the Step S912, theprocessing returns to the Step S911.

[0283] When checking the transmission period in the Step S913, thetransmission periods of the compressed mode frames extracted from eachchannel in the compressed mode are calculated together in a givencombination to form one transmission duration. Then, it is determinedwhether the total times of the combinations include any combinationswhich can fit into one frame duration (Step S914).

[0284] As a result, when there is a combination which can fit into oneframe duration, that combination is used for compressed mode frametransmission by allocating a single spreading code and mutuallydiffering transmission timings to the channels (transmitters) of thecompressed mode frames included in the combination (Step S915). On theother hand, if there are no combinations which can fit into one frameduration, multiple channels cannot be transmitted with a singlespreading code, and so the processing returns to the Step S911.

[0285] As described above, according to the ninth embodiment, in thecompressed mode controller 200, a combination is extracted from givencombinations of multiple compressed mode frames compressed by separateusers in the transmitter group 100, the extracted combination having atotal transmission timing of less than one frame duration, the samespreading code is allocated to each of multiple channels which transmitthe extracted combination, and the transmission timings of thecompressed mode frames which comprise the above extracted combinationsare controlled in such a manner that they do not temporally overlapwithin one frame duration, while using the same spreading code. As aconsequence, when there are multiple compressed mode frames, it ispossible to reduce the number of spreading codes having low spreadingfactors used in the compressed mode. As a result, spreading coderesources can be effectively used in the compressed mode.

[0286] Furthermore, in the ninth embodiment, in the compressed mode, acompressed frame may be divided into the front and rear of the sameframe timing as in the normal mode, and transmitted intermittent incompliance with that arrangement in the same manner as in the secondembodiment described above. Consequently, it is possible to secure anappropriate interleaving time in compressed mode in the same way as inthe normal mode, with a simple interleave constitution. As a result,poor performance caused by interleaving in bit units can be prevented.

[0287] Furthermore, in the ninth embodiment, in the compressed mode, acompressed frame may be slotted and transmitted intermittently in N slotunits in the same manner as in the third embodiment described above.Consequently, it is possible to receive transmission power control bitstransmitted in the downlink in comparatively short time intervals. As aresult, the amount of error in the transmission power control can bereduced.

[0288] In the above explanation, only a sample of an example combinationof the characteristic parts of the embodiments 1 to 9 was shown, andother combinations thereof can of course be realized.

[0289] The embodiments 1 to 9 of the present invention were explainedabove, but various modifications are possible within the range of themain points of the present invention, and these are not excluded fromthe range of the invention.

[0290] The embodiments 1 to 9 described above explain how a period oftime is provided to slot the frame and transmit it intermittently, andthe strength of other frequency carriers is measured usingnon-transmission time, i.e. idle period, during that period. However,the method of establishing synchronization between the mobile stationsand the base station in an actual handover between different frequencieswas not mentioned. Therefore, a communication device capable ofrealizing handovers between different frequencies using the invention,and a method of establishing synchronization thereof, will be explainedbelow.

[0291] Firstly, before describing a handover between differentfrequencies, the constitution of information transmitted and receivedbetween the mobile stations and the base station will be explained.

[0292]FIG. 37 shows a frame constitution of a broadcast channel (BCH).In a W-CDMA system, as shown in FIG. 37(a), one frame of the broadcastchannel comprises sixteen slots, for instance, corresponding to #1 to#16 in the diagram. Furthermore, as shown in FIG. 37(b), one slotcomprises ten symbols (representing one cycle of the spreading code) Inthis constitution, the four symbols shown by “P” in the diagram arepilot symbols needed for detecting phase information, the five symbolsshown by “D1 to D5” in the diagram are information components of thebroadcast channel, and one symbol shown by “FSC” (first search code) and“SSC” (second search code) in the diagram is a search code. The firstsearch code and the second search code are transmitted at the same time.

[0293] Furthermore, in the W-CDMA system, spectrum spreading isperformed using spreading codes, the spreading codes comprising twoelements called a spreading code (short code) specific to the channels,and a scrambling code (long code) specific to the base stations (seeFIG. 37(c) and FIG. 37(d)). The same spreading code is used for thepilot symbol P and the information components D1 to D5, and differentspreading codes (COMMON and C+Walsh in the diagram) are used for thesearch codes. Furthermore, only the search code is not spread by thescrambling code. Next, the normal mode sequence of establishingsynchronization between the base station and the mobile stations in theW-CDMA system will be explained keeping in mind the basic assumption(constitution of the broadcast channel frame) mentioned above.

[0294] In a W-CDMA system, the cells are basically unsynchronized, thatis, the frame timings and the like do not generally match. Accordingly,in the W-CDMA system, the mobile stations and the base stations can besynchronized using, for instance, a three-stage initial acquisitionmethod.

[0295] In the first stage, a first search code (FSC), being transmittedcommonly from all the base station and time-continually, is detected.Using this, slot synchronization can be established.

[0296] In the second stage, multiple second search codes SSC),transmitted at the same timing as the first search code, are detectedcontinuously in sixteen slots, and determined in their transmissionsequence. As a consequence, frame synchronization can be established,and moreover, a scrambling code group number can be identified. Morespecifically, for instance, as shown in FIG. 38, the second search codesare detected in sixteen continuous slots. Then, frame synchronizationcan be accomplished from one cycle comprising #1 to #16 from the secondsearch codes detected in this manner. Moreover, the scrambling codegroup number can be identified based for instance on a correspondencetable such as that shown in FIG. 39. Here, the slot # on the horizontalaxis represent slot numbers, and the groups on the vertical axisrepresent scrambling code groups. Furthermore, there are seventeen typesof second search codes (1 to 17), and from a combination of sixteenslots it is possible to uniformly identify the scrambling code groupnumber, i.e. the scrambling code used by the base station which themobile station belongs to. The numeric values of the second search codesstored in this table are one specific example to explain the presentinvention, and in the sense of identifying a given numeric pattern,other numeric values can of course be used.

[0297] In the third stage, it is identified which of the multiplescrambling codes contained in the scrambling group numbers are beingused, to complete the establishment of synchronization of the downstreamline of the corresponding base station.

[0298]FIG. 40 is a flowchart of a case when the synchronizationestablishment sequence described above is actually being performed onthe mobile station side. Below, the operation of the mobile station willbe explained based on FIG. 37.

[0299] Firstly, the mobile station performs processing corresponding tothe first stage, by detecting the first search code (Step S921).Detection is carried out continuously until a first search code isdetected (Step S922)

[0300] When the first search code has been detected (YES in the StepS922), the mobile station synchronizes the slots, and then detectssixteen second search codes in the second stage (Step S923). Here, atthe mobile station, when a second search code cannot be detected due tothe condition of the channels or the like (NO in Step 924), the numberof undetected places is counted (Step S925), and it is determinedwhether there are more or less of these than a predetermined number setin advance (Step S926). For instance, when there are more of them, thesecond search code is detected again (Step S923), and on the other hand,when there are fewer of them, only that portion is detected (Step S927and Step 928).

[0301] In this way, when all the second search codes have been detected(YES in the Step S924, and YES in the Step 928), as explained above, themobile station establishes frame synchronization, and identifies thescrambling code group number.

[0302] Finally, as the third stage, the mobile station identifies thescrambling code used by the corresponding base station (Step 931, YES inStep 932), completing the establishment of initial synchronization. Thuscommunication becomes possible. When calculating the correlation valueof the identified scrambling codes (Step S933), when all the codes arebelow a predetermined reference value (YES in Step 934), the secondsearch codes are detected again (Step S923); otherwise (NO in the StepS934), the scrambling codes are reidentified until the Step 931 iscompleted.

[0303] On the other hand, as explained earlier (in a case requiring ahandover as explained in the conventional technology), when performing ahandover between different frequencies, the power of other carriers ismeasured in compliance with an order from the base station or adetermination carried out by the mobile station, and if there is acarrier which seems actually capable of a frequency handover, thehandover is carried out according to a predetermined sequence. At thatpoint, a first search code can be detected without fail, i.e., at leastonce in the idle period described in the above embodiments 1 to 9.However, to detect a second search code it is necessary to search oneframe, i.e. all sixteen slots, and consequently it cannot be detected inthis way. Therefore, similarly, it is not possible to detect thescrambling code group number.

[0304] Accordingly, it is an object of the present embodiment to realizea communication device capable of detecting all second search codes bygradually shifting the idle period is of not more than half of oneframe.

[0305]FIG. 41 shows a constitution of a receiver according to a tenthembodiment of the present invention. This constitution is provided tothe mobile stations.

[0306] As shown in FIG. 41, the receiver 2E comprises a controller 21E,an error-correction decoder 22, a deinterleaver 23, adeframing/de-spreading unit 24E, a radio frequency transmitter 25, atime/de-spreading unit 51, a detecting/determining unit 52, and a switch53. Parts of the constitution which are the same as the embodimentsalready described are represented by the same reference codes andexplanation thereof will be omitted.

[0307] Through negotiations with a transmitter not shown in the diagram,the controller 21E mainly controls the operations of the deinterleaver23, the deframing/de-spreading unit 204, and the switch 53. Bynegotiating with the transmitter, this controller 21E indicates framenumbers of the frames to be deinterleaved, appropriate to the normalmode and the compressed mode. Furthermore, in the compressed mode, thiscontroller 21E supplies an instruction to reduce the spreading factor,and reception timings for receiving compressed mode frames, to theswitch 53, the deframing/de-spreading unit 2E, and the time/despreadingunit 51. That is, the switch 53 and the time/despreading unit 51 areconnected only in the idle period.

[0308] The radio frequency receiver 25 decodes received signals sentfrom an antenna not shown in, the diagram. The deframing/de-spreadingunit 24E de-spreads using spreading codes allocated to the users of thereceiver 2E in correspondence with the normal mode and the compressedmode, and forms a frame for each mode. When the controller 21E hasinstructed the deframing/de-spreading unit 24E of reception timings incorrespondence with each of the modes, the deframing/de-spreading unit24E extracts the received signals from the radio frequency receiver 25in accordance with the reception timings. Furthermore, in the compressedmode, the deframing/de-spreading unit 24E receives an instruction fromthe controller 21F to reduce the spreading factor, and, in accordancewith that instruction, obtains a received signal using a lower spreadingfactor than in the normal mode. The deinterleaver 23 chronologicallyinterleaves (deinterleaves) the coded data in bit units, in a reversesequence to the interleaving in the transmitter. The error-correctiondecoder 22 corrects errors in the deinterleaved signal to obtain decodeddata, i.e. a received data stream.

[0309] Furthermore, during the idle period, the time/de-spreading unit51 detects first search codes and second search codes on other carriers.The detecting/determining unit 52 carries out a determining process,described later, based on the detected first search codes and secondsearch codes.

[0310] The receiver 2E having the constitution as shown in FIG. 42normally receives a compressed frame on a carrier (frequency: f1) beingused in communication. In idle period this receiver 2E receives thesearch code on another carrier (frequency: f2).

[0311] Next, the operation in the receiver 2E when performing a handoverwill be explained. FIG. 43 is a flowchart of the procedures ofestablishing synchronization performed on the mobile station side duringa handover between W-CDMA/W-CDMA different frequencies. In the handoverexplained below, the controller 21E carries out control based on adetermination of the detecting/determining unit 52.

[0312] For instance, in the case of a handover performed in accordancewith a command from the base station or a determination of the mobilestation, the mobile station extracts cell information of other frequencycarriers from the base station (Step S941).

[0313] Next, based on the extracted information, the mobile stationcarries out processing corresponding to the first stage by detecting afirst search code and a different frequency carrier during the idleperiod of the compressed mode (Step S942). Basically, this detecting isperformed continuously until the first search code is detected (StepS943), but returns to redetecting the cell information and the firstsearch code in accordance with a setting of the receiver (Step S944).During the idle period, the switch 53 is connected to thetiming/de-spreading unit 51 in compliance with the controller 21E.

[0314] When the first search code and the different frequency carrierhave been detected (YES in the Step S943), the mobile stationestablishes slot synchronization, and then dejects sixteen second searchcodes in the second stage (Step S945). As the second search codedetection, as for instance shown in FIG. 44, the controller 21E shiftsthe idle period for each slot, and detects one second search code ineach frame. That is, all the second search codes are detected in sixteenframes.

[0315] Furthermore, the method of detecting the second search code isnot restricted to this, and two second search codes may be detected inone frame, as for instance shown in FIG. 45. This case differs form FIG.44 in that all the second search codes can be detected in eight frames.Furthermore, when continuously controlling multiple frames (two framesare shown in the diagram), as for instance shown in FIG. 46 and FIG. 47,all the second search codes can be detected by setting the idle period.As explained above, the idle period needs only to be set to a maximum ofhalf the duration of one frame, there being many conceivable variationsother than the above. Therefore, the number of frames detected variesaccording to the length of the idle period. Furthermore, detectionreliability can be improved by detecting all the second search codes anumber of times.

[0316] However, when the idle period is set long, although the detectiontime does not take longer than when the idle period is short, there maybe some deterioration in the quality of information data that was beingtransmitted, or interference power may be increased if the transmissionpower is increased to maintain the quality of this data. On the otherhand, when the idle period is shortened, although there is not as muchdeterioration in the quality of information data as compared to when theidle period is long, the detection time is much longer. Accordingly, anoptimum idle period must be set at the receiver side, with considerationto synthesizer performance (synthesizer switching time and the like) andthe channel condition and the like. Furthermore, the portions in theframes of FIG. 45 to FIG. 47 where the slots overlap must be set asappropriate in accordance with synthesizer performance (synthesizerswitching time and the like).

[0317] In the Step S945, when the mobile station is unable to detect asecond search code due to the condition of the channel (NO in StepS924), the number of undetected places is counted (Step S925), and it isdetermined whether there are more or fewer than a predetermined number(Step S926); for instance, when there are more, the second search codesare detected again, on the other hand, when there are fewer, detectingis carried out in that portion only.

[0318] In this way, when all the second search codes have been detected(YES in the Step S924, or YES in the Step 928), the mobile stationestablishes frame synchronization to the other carrier, and identifiesthe scrambling code group number of the corresponding base station.

[0319] Finally, as the third stage, the mobile station identifies thescrambling code used by the corresponding base station (Step 931, YES inStep 932), completing the establishment of initial synchronization inthe handover. Thus communication is possible. When calculating thecorrelation value of the identified scrambling codes (Step S933), whenall the codes are below a predetermined reference value (YES in Step934), the second search codes are detected again (Step S923); otherwise(NO in the Step S934), the scrambling codes are reidentified until theStep 931 is completed.

[0320] Next, a handover operation with another communication systemknown as GSM (Global System for Mobile Communication) will be explainedusing the diagrams. This handover is also performed at the receiver 2Eshown in FIG. 41. Therefore, in this case, instead of the first searchcodes and the second search codes, the time/de-spreader 51 detects FCCHand SCH explained below.

[0321]FIG. 48 is a diagram showing a constitution of a GSM superframe.FIG. 48(a) is a GSM control channel, that is, a channel showing controlinformation such as a Frequency Correction CH (FCCH) for tuningfrequencies, a Synchronization CH (SCH) for synchronizing, as well asother information. FIG. 48(b) shows a GSM Traffic CH (TCH). Furthermore,FIG. 49 is a flowchart in a case when a mobile station establishessynchronization in a handover between W-CDMA and GSM.

[0322] Firstly, as a first stage, the W-CDMA mobile station mustdiscover where the GSM frequency carrier is, and so repeatedly coarselymeasures power until it finds the carrier (Step S951 and Step S952).

[0323] Next, when the mobile station has finished power measurement, asa second stage, based on the measurement result, it finely adjusts thecarrier frequency, measured by capturing the FCCH, and identifies theGSM carrier (Step S953). In the GSM, one superframe comprises fifty-oneframes, including five FCCH. Therefore, the W-CDMA system mobile stationtunes the frequency in these five periods (Step S954 and Step S955).Furthermore, the FCCH can be detected without shifting the idle period,by utilizing the fixed time difference between the FCCH/SCH superframesynchronization and the superframe synchronization in the W-CDMA system.However, the FCCH can be detected by gradually shifting the idle period,in the same way as in the above-mentioned handover between W-CDMAsystems.

[0324] Finally, when the GSM carrier has been identified, as a thirdstage, the mobile station capture the SCH, which is the frame next tothe FCCH, and synchronizes the bit timings (Step S956, Step S957, andStep S958). For instance, if the detection of the FCCH is complete, theposition of the SCH is already known (it is the next frame) and thus itcan easily be detected. Therefore, although it is necessary to identifyall the superframes to detect the FCCH, the SCH can be detected merelyby setting the idle period so that the frame next to the FCCH can bedetected. However, when detecting the SCH, there is no need to capturethe SCH immediately after the captured FCCH; for instance, the SCHimmediately after the next FCCH can be captured, or any SCH can becaptured. As a consequence, the W-CDMA system mobile station completesthe establishment of initial synchronization in the handover, enablingcommunication with the GSM to be carried out.

[0325] In this way, according to the present embodiment, a handover caneasily be achieved between different frequencies (between a W-CDMAsystem and a W-CDMA system, and between a W-CDMA system and a GSM).

[0326] The above embodiments 1 to 10 describes in detail the spreadspectrum communication device of the present invention, and theoperations of these embodiments share the process of using aninterleaver to chronologically interleave in bit units coded data, andthereafter, using a framing/spreading unit to compress the interleaveddata. However, the interleaving of data does not necessarily have to beperformed prior to compression, and can basically be performed in anypoint. For instance, the interleaving may be performed after the datahas been compressed. Therefore, when interleaving after the data hasbeen compressed, the error-correction encoder has the function ofcompressing the data, and there is no need for provide aframing/spreading unit. In such a case, the constitution of the receiverside naturally changes. That is, the deinterleave processing isperformed first.

INDUSTRIAL APPLICABILITY

[0327] As above, the spread spectrum communication device according tothe present invention is useful for a code division multiple access(CDMA) communication system, and is especially applicable to spreadspectrum communication carrying out interleaving transmission andtransmission power control, and moreover, is applicable as acommunication device for carrying out a handover between differentfrequencies (between a W-CDMA system and a W-CDMA system, and between aW-CDMA system and a GSM).

1. A spread spectrum communication device applied in a code divisionmultiple access system for continuously transmitting frames in a normalmode and intermittently transmitting compressed frames in a compressedmode, said device comprising: an interleaving unit for interleaving inbit units a frame or a compressed frame, which is a unit of atransmission data stream, to minimize effects of transmission errors; acompressing/intermittent transmitting unit for compressing a frame priorto or after interleaving in the compressed mode, and moreover,intermittently outputting the compressed frame to said interleaving unitif the compressed frame has not yet been interleaved, and intermittentlyoutputting the compressed frame to a device on a receiving side if thecompressed frame has been interleaved; and a control unit forcontrolling the interleaving in bit units operation of said interleavingunit, and the compressing/intermittent transmitting operation of saidcompressing/intermittent transmitting unit; wherein said control unitcontrols said interleaving unit so as to perform interleaving in bitunits across multiple frames in the compressed mode.
 2. The spreadspectrum communication device according to claim 1, characterized inthat said interleaving unit has a memory size in correspondence with thenumber of frames to be interleaved in the compressed mode.
 3. A spreadspectrum communication device applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode andintermittently transmitting compressed frames in a compressed mode, saiddevice comprising: an interleaving unit for interleaving in bit units aframe or a compressed frame, which is a unit of a transmission datastream, to minimize effects of transmission errors; acompressing/intermittent transmitting unit for compressing a frame priorto or after interleaving in the compressed mode, and moreover,intermittently outputting the compressed frame to said interleaving unitif the compressed frame has not yet been interleaved, and intermittentlyoutputting the compressed frame to a device on a receiving side if thecompressed frame has been interleaved; and a control unit forcontrolling the interleaving in bit units operation of said interleavingunit, and the compressing/intermittent transmitting operation of saidcompressing/intermittent transmitting unit; wherein said control unitcontrols said compressing/intermittent transmitting unit so as to dividethe compressed frame into the front and rear of the same frame timing asin the normal mode.
 4. The spread spectrum communication deviceaccording to claim 3, characterized in that said control unit controlssaid interleaving unit so that, in the compressed mode, interleaving inbit units is performed across multiple frames.
 5. A spread spectrumcommunication device applied in a code division multiple access systemfor continuously transmitting multiple frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, saiddevice comprising: a compressing/intermittent transmitting unit for, inthe compressed mode, compressing a frame, which comprises multiple slotsand is a unit of a transmission data stream, and intermittentlytransmitting the compressed frame; and a control unit for controllingsaid compressing/intermittent transmitting unit so as to slot thecompressed frame, and intermittently transmit the slotted frame in N (anatural number) slot units.
 6. The spread spectrum communication deviceaccording to claim 5, characterized in that said control unit determinethe N slot units in accordance with the relationship between measuringperiod of other frequency carrier components and the amount oftransmission power control error.
 7. The spread spectrum communicationdevice according to claim 5 further comprises an interleaving unit forinterleaving in bit units a frame or a compressed frame, which is a unitof a transmission data stream, to minimize effects of transmissionerrors; wherein said control unit controls said interleaving unit sothat, in the compressed mode, interleaving in bit units is performedacross multiple frames.
 8. A spread spectrum communication deviceapplied in a code division multiple access system for continuouslytransmitting frames in a normal mode, and intermittently transmittingcompressed frames in a compressed mode, said device comprising: aninterleaving unit for interleaving in bit units a frame or a compressedframe, which is a unit of a transmission data stream, to minimizeeffects of transmission errors; a compressing/intermittent transmittingunit for compressing a frame prior to or after interleaving in thecompressed mode, and moreover, intermittently outputting the compressedframe to said interleaving unit if the compressed frame has not yet beeninterleaved, and intermittently outputting the compressed frame to adevice on a receiving side if the compressed frame has been interleaved;and a control unit for controlling the interleaving in bit unitsoperation of said interleaving unit, and the compressing/intermittenttransmitting operation of said compressing/intermittent transmittingunit; wherein in said compressed mode, said control unit controls saidcompressing/intermittent transmitting unit so that multiple frames priorto interleaving in bit units by said interleaving unit, or multipleframe after interleaving has been performed, are compressed usingcode-multiplexing in a given frame timing.
 9. The spread spectrumcommunication device according to claim 8, characterized in that saidcontrol unit controls said interleaving unit so that, in the compressedmode, interleaving in bit units is performed across multiple frames. 10.The spread spectrum communication device according to claim 8,characterized in that said compressing/intermittent transmitting unithas a memory size in correspondence with the number of frames to becode-multiplexed in said compressed mode.
 11. A spread spectrumcommunication device applied in a code division multiple access systemfor continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, saiddevice comprising: a compressing/intermittent transmitting unit forcompressing a frame, which is a un it of a transmission data stream, andintermittently transmitting the compressed frame, in said compressedmode; and a control unit for controlling said compressing/intermittenttransmitting unit so that, in the compressed mode, saidcompressing/intermittent transmitting unit intermittently transmit at alower transmission rate than the transmission rate in the normal mode,while using the same transmission power as in the normal mode.
 12. Thespread spectrum communication device according to claim 11 furthercomprises an interleaving unit for interleaving in bit units a frame ora compressed frame, which is a unit of a transmission data stream, tominimize effects of transmission errors; wherein said control unitcontrols said interleaving unit so that, in the compressed mode,interleaving in bit units is performed across multiple frames.
 13. Thespread spectrum communication device according to claim 11,characterized in that said control unit controls saidcompressing/intermittent transmitting unit so as to divide thecompressed frame into the front and rear of the same frame timing as inthe normal mode.
 14. The spread spectrum communication device accordingto claim 11, characterized in that said control unit controls saidcompressing/intermittent transmitting unit so as to slot said compressedframe, and intermittently transmit the slotted frame in N (a naturalnumber) slot units.
 15. A spread spectrum communication device appliedin a code division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said device comprising: a memory unit forstoring the units of optimum transmission power control for the normalmode and the compressed mode, in such a way that the units oftransmission power control for controlling one input of transmissionpower are greater in the compressed mode as compared to the normal mode;and a transmission power control unit for referring to said memory unit,and controlling transmission power to a communication partner device incompliance with the units of transmission power control incorrespondence with the normal mode and the compressed mode, based oninformation representing a reception power received from saidcommunication partner device.
 16. The spread spectrum communicationdevice according to claim 15 further comprises acompressing/intermittent transmitting unit for compressing a frame,which comprises multiple slots and is a unit of a transmission datastream, and intermittently transmitting the compressed frame; and acontrol unit for controlling said compressing/intermittent transmittingunit so as to slot the compressed frame, and intermittently transmit theslotted frame in N (a natural number) slot units.
 17. A spread spectrumcommunication device applied in a code division multiple access systemfor continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, saiddevice comprising: a memory unit for taking more multiple types of unitsof transmission power control than in the normal mode, a transmissionpower control for controlling one input of transmission power, includingamong the multiple types of units of transmission power control a unitof transmission power control which is greater than in the normal mode,and storing optimum units of transmission power control for the normalmode and compressed mode; and a transmission power control unit forreferring to said memory unit, and controlling transmission power to acommunication partner device in compliance with the units oftransmission power control in correspondence with the normal mode andthe compressed mode, and in addition, in correspondence with temporalintervals in the transmission power control in the compressed mode,based on information representing a reception power received from saidcommunication partner device.
 18. The spread spectrum communicationdevice according to claim 17 further comprises acompressing/intermittent transmitting unit for, in the compressed mode,compressing a frame, which comprises multiple slots and is a unit of atransmission data stream, and intermittently transmitting the compressedframe; and a control unit for controlling said compressing/intermittenttransmitting unit so as to slot the compressed frame, and intermittentlytransmit the slotted frame in N (a natural number) slot units.
 19. Aspread spectrum communication device applied in a code division multipleaccess system for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, saiddevice comprising: a transmission section for using a desired spreadingcode to create transmission data of a quantity corresponding to a numberof users who can be served thereby, in correspondence with the normalmode and the compressed mode, and adding and transmitting thetransmission data created in correspondence with the number of users;and a compressed mode control section, connected to said transmissionsection, for controlling the creation operation of transmission data bysaid transmission section in said compressed mode; said compressed modecontrol section having a frame combining unit for extracting from givencombinations of multiple compressed mode frames, compressed by separateusers in said transmission section, a combination having a totaltransmission duration of less than one frame duration; a spreading codeallocation unit for allocating the same spreading code to each ofmultiple channels which transmit the combination extracted by said framecombining unit; and a transmission timing control unit for using asingle spreading code, allocated by said spreading code allocation unit,to control said transmission section so that transmission timings ofmultiple compressed mode frames, which comprise the above extractedcombination, do not temporally overlap within one frame duration.
 20. Aspread spectrum communication device applied in a code division multipleaccess system for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, saiddevice comprising: a compressing/intermittent receiving unit forintermittently receiving a compressed frame in the compressed mode; asearch code detecting and determining unit for detecting in otherfrequency carriers, during non-transmission period in the compressedmode, a first search code, which is shared at all base stations and istime-continually transmitted, and a second search code, which istransmitted at the same time as the first search code and can beidentified by multiple numeric patterns, and determining these searchcodes based on a predetermined reference; and a control unit forselecting said compressing/intermittent receiving unit duringintermittent receiving, selecting said search code detecting anddetermining unit during non-transmission period, and controllingoperations of both; wherein said control unit establishessynchronization to the other frequency carrier, based on the firstsearch code and second search code detected by said search codedetecting and determining unit, and thereby controlling a handoverbetween different frequencies.
 21. The spread spectrum communicationdevice according to claim 20 wherein said control unit carries outcontrol to detect at least one first search code during not more thanhalf of one frame in the non-transmission period, thereafter, carriesout control to repeat the processing of shifting the non-transmissionperiod by a predetermined slot unit, and to detect a numeric value ofall second search codes using multiple frames, and establishsynchronization to the other frequency carrier, based on the numericpattern of the detected first search code and second search code,thereby controlling a handover between different frequencies.
 22. Thespread spectrum communication device according to claim 21, wherein thenon-transmission duration can be arranged across multiple frames. 23.The spread spectrum communication device according to claim 22,characterized in that, when no search code can be obtained whichsatisfies a predetermined level of reliability during the search codedetection, a search code is detected again in the place.
 24. A spreadspectrum communication device applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, saiddevice comprising: a compressing/intermittent receiving unit forintermittently receiving a compressed frame in the compressed mode; aninformation detecting and determining unit for detecting in anothercommunication system, during non-transmission period in the compressedmode, a first information for tuning frequencies, and a secondinformation for achieving synchronization, and determining the first andsecond information based on a predetermined reference; and a controlunit for selecting said compressing/intermittent receiving unit duringintermittent receiving, selecting said information detecting anddetermining unit during non-transmission period, and controllingoperations of both; wherein said control unit establishessynchronization to the other communication system, based on the firstinformation and second information detected by said informationdetecting and determining unit, and thereby controlling a handoverbetween different frequencies.
 25. The spread spectrum communicationdevice according to claim 24, wherein said control unit carries outcontrol to detect at least one first information during thenon-transmission period which is not more than half of one frame,thereafter, carries out control to set the non-transmission period basedon a time predetermined by the detected first information, and to detectthe second information, and establishes synchronization to said othercommunication system, based on the detected first information and secondinformation, thereby controlling a handover between differentfrequencies.
 26. A spread spectrum communication method applied in acode division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said method comprising: a first step ofinterleaving bit units across multiple frames, in order to minimizeeffects of transmission errors, in the compressed mode; a second step ofcompressing a frame interleaved in bit units in said first step, andintermittently transmitting it.
 27. A spread spectrum communicationmethod applied in a code division multiple access system forcontinuously transmitting frames in a normal mode, and intermittentlytransmitting compressed frames in a compressed mode, said methodcomprising: a first step of compressing a frame, which is a unit of atransmission data stream, and intermittently outputting it, in thecompressed mode; and a second step of interleaving bit units across aplurality of the compressed frames.
 28. A spread spectrum communicationmethod applied in a code division multiple access system forcontinuously transmitting frames in a normal mode, and intermittentlytransmitting compressed frames in a compressed mode, said methodcomprising: a first step of interleaving bit units of a frame, which isa unit of a transmission data stream, in order to minimize effects oftransmission errors; and a second step, performed in the compressedmode, of compressing a frame interleaved in bit units in said firststep, dividing the compressed frame to the front and rear of the sameframe timing as in the normal mode, and intermittently transmitting it.29. A spread spectrum communication method applied in a code divisionmultiple access system for continuously transmitting frames in a normalmode, and intermittently transmitting compressed frames in a compressedmode, said method comprising: a first step, performed in the compressedmode, of compressing a frame, which is a unit of a transmission datastream, and interleaving bit units of the compressed frame; and a secondstep of dividing the compressed and interleaved frame to the front andrear of the same frame timing as in the normal mode, and intermittentlytransmitting it.
 30. A spread spectrum communication method applied in acode division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said method comprising: a first step ofdividing a frame, which is a unit of a transmission data stream, intomultiple slots in the compressed mode; and a second step ofintermittently transmitting the frame slotted in said first step in N(N=a natural number) slot units.
 31. A spread spectrum communicationmethod applied in a code division multiple access system forcontinuously transmitting frames in a normal mode, and intermittentlytransmitting compressed frames in a compressed mode, said methodcomprising: a first step of interleaving in bit units a frame, which isa unit of a transmission data stream, in order to minimize effects oftransmission errors; a second step, performed in the compressed mode, ofusing code-multiplexing to compress, in a given frame timing, multipleframes interleaved in bit units in said first step, and output themintermittently.
 32. A spread spectrum communication method applied in acode division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said method comprising: a first step,performed in the compressed mode, of using code-multiplexing tocompress, in a given frame timing, multiple frames and output- themintermittently; and a second step of interleaving the compressed framesin bit units.
 33. A spread spectrum communication method applied in acode division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said method comprising: a first step ofcompressing a frame, which is a unit of a transmission data stream, inthe compressed mode; and a second step of using the same transmissionpower as in the normal mode to transmit intermittently the framecompressed in said first step at a lower transmission rate than in thenormal mode.
 34. A spread spectrum communication method applied in acode division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said method comprising: a first step ofreceiving information representing reception power from a communicationpartner device; a second step of preparing beforehand a table storingoptimum units of transmission power control for the normal mode and thecompressed mode, so that the unit of transmission power control forcontrolling one input of transmission power is greater in the compressedmode than in the normal mode, referring to this table, and determiningtransmission powers for the normal mode and the compressed mode, basedon the information representing reception powers received in said firststep; and a third step of transmitting to said communication partnerdevice in compliance with the transmission powers determined in saidsecond step.
 35. A spread spectrum communication method applied in acode division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said method comprising: a first step ofreceiving information representing reception power from a communicationpartner device; a second step of taking more multiple types of units oftransmission power control than in the normal mode, a transmission powercontrol for controlling one input of transmission power, included amongthe multiple types of units of transmission power control a unit oftransmission power control which is greater than in the normal mode,preparing beforehand a table storing optimum units of transmission powercontrol for the normal mode and compressed mode, referring to saidtable, and determining transmission power in correspondence with thenormal mode and the compressed mode, and in addition, in correspondencewith temporal intervals in the transmission power control in thecompressed mode, based on information representing a reception powerreceived in said first step; and a third step of transmitting to saidcommunication partner device in compliance with the transmission powersdetermined in said second step.
 36. A spread spectrum communicationmethod applied in a code division multiple access system forcontinuously transmitting frames in a normal mode, and intermittentlytransmitting compressed frames in a compressed mode, said methodcomprising: a first step of compressing frames, which are units of atransmission data stream, in multiple transmission channels performingcompressed mode transmission; a second step of extracting from givencombinations of multiple compressed mode frames, compressed separatelyfor users in said first step, a combination having a total transmissionduration of less than one frame duration; a third step of allocating thesame spreading code to each of multiple channels for transmittingmultiple compressed mode frames which comprise the combination extractedin said second step; and a fourth step of using a single spreading code,allocated in said third step, to transmit multiple compressed modeframes, which comprise the combination extracted in said third step, sothat their transmission timings do not temporally overlap within oneframe duration.
 37. A spread spectrum communication method applied in acode division multiple access system for continuously transmittingframes in a normal mode, and intermittently transmitting compressedframes in a compressed mode, said method comprising: a first search codedetecting step of detecting at least one first search code in not morethan half of one frame during the non-transmission period; and a secondsearch code detecting step of thereafter repeating the processing ofshifting the non-transmission period in units of predetermined slots,and detecting a numeric value of all second search codes using multipleframes; wherein a handover between different frequencies is controlledby establishing synchronization to another frequency carrier, based onthe numeric pattern of the detected first search code and second searchcode.
 38. The spread spectrum communication method according to claim34, wherein the non-transmission period can be arranged across multipleframes.
 39. The spread spectrum communication method according to claim35, characterized in that, when no search code can be obtained whichsatisfies a predetermined level of reliability during said search codedetection, a search code is detected again in the place.
 40. A spreadspectrum communication method applied in a code division multiple accesssystem for continuously transmitting frames in a normal mode, andintermittently transmitting compressed frames in a compressed mode, saidmethod comprising: a first information detecting step of detecting afirst information for tuning frequencies in not more than half of oneframe during the non-transmission period; and a second informationdetecting step of detecting second information for setting thenon-transmission period, based on the timing determined beforehand fromsaid detected first information, and achieving synchronization; whereina handover between different frequencies is controlled by establishingsynchronization to another communication system, based on the detectedfirst information and second information.